Hall Effect Current Sensor with Nonmagnetic Spacer
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Solution Overview
Problem
Current sensors with magnetic circuits suffer from reduced accuracy due to magnetic hysteresis and environmental dependencies, particularly when sensing smaller currents.
Innovation Solution
A Hall effect current sensor design featuring a Hall effect generator chip mounted between nonmagnetic spacers and ferromagnetic rings with small air gaps, utilizing high permeability permalloy ferromagnetic rings and a temperature compensation circuit to enhance sensitivity, linearity, and reduce hysteresis and temperature variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a magnetic circuit core is used to concentrate the magnetic field, then the magnetic field strength is improved, but magnetic hysteresis increases affecting measurement accuracy
Solution Approach 1:
The patent removes the magnetic circuit core from the sensor structure, replacing it with a nonmagnetic spacer. This extraction eliminates the magnetic hysteresis effect that plagues traditional designs while preserving the magnetic field concentration function through geometric design of the air gap and Hall device positioning.
Solution Approach 2:
The patent introduces a nonmagnetic spacer as an intermediary element between the conductor and Hall device. This spacer serves as a mediator that maintains precise geometric spacing and positioning without introducing magnetic hysteresis, enabling accurate measurement while concentrating the magnetic field through its structural geometry.
2Measurement precision
If the air gap is reduced to improve sensitivity, then measurement precision improves, but manufacturing precision requirements increase
Solution Approach 1:
The nonmagnetic spacer is pre-formed with the air gap dimension built into its structure during manufacturing. This preliminary action of creating the spacer with integrated spacing features eliminates the need for precise post-assembly adjustments, reducing manufacturing complexity while maintaining small, optimized air gap dimensions for high sensitivity.
Solution Approach 2:
The patent employs a thin nonmagnetic spacer that provides precise dimensional control through its engineered thickness. This thin film approach allows for consistent, small air gap dimensions to be achieved through standard manufacturing processes without requiring exotic precision machining or assembly techniques.
3Reliability
If temperature compensation is added to reduce temperature variation, then reliability improves, but device complexity increases
Solution Approach 1:
The patent implements temperature compensation through self-service mechanisms inherent in the Hall device and its biasing circuitry. The design uses the device's own characteristics and simple circuit elements to automatically compensate for temperature effects, achieving reliable temperature-stable operation without adding complex external compensation circuits or sensors.
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 high sensitivity and linearity with reduced hysteresis and temperature variation, maintaining accuracy across varying temperatures and current ranges, with experimental results showing minimal hysteresis and consistent output within the tested temperature range.
Implementation Method 1
A Hall effect current sensor design featuring a Hall effect generator chip mounted between nonmagnetic spacers and ferromagnetic rings with small air gaps
Implementation Method 2
utilizing high permeability permalloy ferromagnetic rings
Data Source
AI summary
A Hall effect generator chip is mounted between adjacent ends of an annular, horseshoe spacer of nonmagnetic material. The generator is sensitive to the flux density (B field) tangential to its top and bottom surfaces. The spacer and generator are sandwiched between ferromagnetic rings, each having a small air gap overlying/underlying the generator. A circuit including the generator supplies an output linearly proportional to the current of an adjacent conductor with reduced hysteresis and small variability over a temperature range.