Integrated Hall Effect Current Sensor with Eddy Current Shield
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Solution Overview
Problem
Conventional electrical current sensors using Hall effect magnetic field transducers are large, prone to interference from stray magnetic fields and electromagnetic noise, and suffer from issues like 'gate leakage' due to trapped charge at the interface between the sensor die and its encapsulation.
Innovation Solution
A miniaturized current sensor design featuring a Hall effect sensor with an electromagnetic shield and a magnetic core that reduces eddy currents and trapped charge effects, maintaining sensitivity and accuracy while minimizing the impact of external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional Hall effect current sensor with gapped toroid magnetic flux concentrator is used, then the sensor can detect current through the conductor, but the sensor becomes undesirably large in terms of height and circuit board area
Solution Approach 1:
The magnetic flux concentrator is positioned directly on the circuit board with the Hall effect sensor nested within its gap structure. The conductor passes through the center of the toroid, creating a compact nested arrangement where components occupy overlapping spatial volumes rather than separate areas, thereby reducing overall sensor footprint on the circuit board.
Solution Approach 2:
The magnetic flux concentrator uses a three-dimensional toroidal structure with a central gap, transitioning from a two-dimensional planar layout to a three-dimensional configuration. This allows the magnetic flux to be concentrated in the vertical dimension through the conductor, enabling compact sensor design that maintains detection capability while reducing circuit board area occupation.
2Object-affected harmful factors
If an electromagnetic shield is added to reduce electromagnetic noise and eddy currents, then the sensor's susceptibility to interference is reduced, but the device complexity increases
Solution Approach 1:
An electromagnetic shield is introduced as an intermediary component between the external environment and the Hall effect sensor. The shield acts as a mediator that blocks electromagnetic noise and eddy currents from reaching the sensitive sensor elements, while being positioned strategically to minimize structural complexity additions.
Solution Approach 2:
The electromagnetic shield is applied selectively in specific regions where electromagnetic interference is most problematic, rather than enclosing the entire sensor assembly. This localized shielding approach reduces the overall complexity addition while effectively protecting the critical sensor areas from noise and eddy currents.
3Volume of moving object
If the sensor is miniaturized to reduce height and area, then the sensor occupies less space, but the sensitivity and accuracy may be compromised
Solution Approach 1:
The magnetic flux concentrator is constructed from high-permeability magnetic material that efficiently concentrates magnetic flux within a compact volume. This composite structure with optimized magnetic properties enables the sensor to maintain high sensitivity and accuracy despite the reduced size, as the concentrated flux enhances the magnetic field strength at the Hall effect sensor location.
Solution Approach 2:
The magnetic flux concentrator is designed and positioned in advance to pre-concentrate the magnetic flux generated by the conductor before it reaches the Hall effect sensor. This preliminary flux concentration action ensures that even in a miniaturized configuration, the sensor receives sufficient magnetic field strength to maintain measurement precision and sensitivity.
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 results in a compact, sensitive, and accurate current sensor with reduced susceptibility to stray magnetic fields and electromagnetic noise, improving performance and reliability.
Implementation Method 1
one type of conventional electrical current sensor uses a Hall effect magnetic field transducer in proximity to a current-carrying conductor. The Hall effect device generates an output signal having a magnitude proportional to the magnetic field induced by the current through the conductor
Implementation Method 2
The electromagnetic shield has at least one feature selected to reduce an eddy current induced in the electromagnetic shield
Data Source
AI summary
An integrated current sensor includes a current conductor, a magnetic field transducer, and an electromagnetic shield. The magnetic field transducer includes a sensor die. The electromagnetic shield is disposed proximate to the sensor die. The electromagnetic shield has at least one feature selected to reduce an eddy current in the electromagnetic shield.