PCB Planar Coil Current Sensor for Low-Current Precision
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Solution Overview
Problem
Conventional current sensor assemblies struggle to accurately measure low currents due to the weak magnetic fields induced, resistance/inductance constraints, and cost considerations.
Innovation Solution
The development of current sensor assemblies featuring conductive coil or loop structures formed on printed circuit boards (PCBs) assembled with differential magnetic field sensors, or integrated as part of the sensors themselves, allowing for accurate measurement of low currents while being cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current sensor assemblies are used, then cost is reduced, but measurement precision of low currents deteriorates due to weak magnetic fields
Solution Approach 1:
The patent transitions from traditional three-dimensional coil structures to two-dimensional planar coil structures fabricated on PCB substrates. This dimensional reduction enables integration with planar magnetic field sensors while maintaining effective sensing area, thereby improving measurement precision for low currents through enhanced magnetic coupling in the planar configuration.
Solution Approach 2:
The patent employs composite construction by integrating conductive trace structures on PCB substrates with magnetic field sensing elements. The combination of conductive traces, magnetic flux concentrators, and differential magnetic field sensors creates a composite assembly that achieves high measurement precision while utilizing cost-effective PCB fabrication processes.
2Measurement precision
If conventional current sensor assemblies are used, then device complexity is reduced, but measurement precision of low currents deteriorates due to resistance and inductance constraints
Solution Approach 1:
The patent divides the current sensing function into separate modular components: conductive trace structures for magnetic field generation, magnetic flux concentrators for field enhancement, and differential magnetic field sensors for detection. This segmentation allows each component to be optimized independently and facilitates integration while managing device complexity through modular assembly.
Solution Approach 2:
The patent introduces magnetic flux concentrators as intermediary elements between the conductive trace structures and the magnetic field sensors. These concentrators mediate the magnetic field interaction by concentrating and directing magnetic flux lines, thereby enhancing the coupling between the traces and sensors without requiring direct physical contact or complex integration.
3Measurement precision
If differential magnetic field sensors are integrated with PCB coil structures, then measurement precision of low currents is improved, but device complexity increases
Solution Approach 1:
The patent merges the coil structure and magnetic field sensors into a single integrated assembly fabricated on a common PCB substrate. The conductive traces, magnetic flux concentrators, and differential magnetic field sensors are co-integrated in a planar configuration, reducing the number of discrete components and interconnections while achieving enhanced measurement precision through improved magnetic coupling.
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
These embodiments enable accurate measurement of low currents, improve the magnetic coupling factor, and provide a cost-effective solution for current sensing applications, including differential current sensing.
Implementation Method 1
the coil structure configured to generate a differential magnetic field responsive to an electrical current passing through the first and second coils
Implementation Method 2
a first magnetic field sensing element disposed proximate to the first coil and operable to generate a first signal responsive to the differential magnetic field passing through the first magnetic field sensing element
Data Source
AI summary
A current sensor assembly can include: a coil structure having a first coil and a second coil connected in series, the coil structure configured to generate a differential magnetic field responsive to an electrical current passing through the first and second coils; a first magnetic field sensing element disposed proximate to the first coil and operable to generate a first signal responsive to the differential magnetic field passing through the first magnetic field sensing element in a first direction; a second magnetic field sensing element disposed proximate to the second coil and operable to generate a second signal responsive to the differential magnetic field passing through the second magnetic field sensing element in a second direction; and a circuit operable to subtract the first and second signals to generate a differential signal proportional to the electrical current.