Built-In Switch Current Sensor Using Differential Magnetic Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensors, particularly those used in automobile control systems, face challenges in meeting stringent safety and quality requirements due to issues with electromagnetic interference and stray field sensitivity, which affect their reliability and accuracy in measuring electrical current.
Innovation Solution
A current sensor apparatus is designed with a substrate, switching device, and magnetic field sensing elements arranged in specific patterns to form a sensing circuit, encapsulated in a semiconductor package, which measures electrical current through contact members while minimizing interference from stray fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensing elements are used to measure electrical current, then measurement capability is provided, but sensitivity to stray fields causes measurement errors and reduced reliability
Solution Approach 1:
The patent applies differential measurement using multiple magnetic field sensing elements (first, second, third, and fourth sensing elements) arranged around the contact member. By measuring magnetic fields at multiple positions and calculating differences between adjacent sensing elements, the system converts the harmful stray field effect into a useful differential signal that cancels out common-mode interference while preserving the current measurement information.
Solution Approach 2:
The patent introduces dielectric layers and structural arrangements as intermediaries between the contact member and magnetic field sensing elements. These intermediate structures help isolate and characterize the magnetic field paths, allowing the sensing elements to distinguish between fields generated by the contact member current and external stray fields.
2Reliability
If electromagnetic flux sensing elements are used in safety-critical applications, then current measurement function is provided, but electromagnetic interference affects functional safety and reliability
Solution Approach 1:
The patent uses differential measurement across multiple sensing elements to convert electromagnetic interference into a cancelable common-mode signal. By computing the difference between adjacent sensing element outputs, the system eliminates EMI effects that appear equally across all sensors while preserving the differential current measurement signal.
Solution Approach 2:
The patent divides the measurement function into multiple segmented sensing elements distributed around the contact member. This segmentation allows independent measurement at each position and enables differential processing that rejects common-mode electromagnetic interference while maintaining accurate current measurement capability.
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 solution provides accurate and reliable measurement of electrical current by reducing interference from stray fields, ensuring compliance with safety and quality standards, and enabling effective overcurrent protection.
Implementation Method 1
Some sensors include one or more electromagnetic flux sensing elements, such as a Hall effect element
Implementation Method 2
Some sensors include one or more electromagnetic flux sensing elements, such as a Hall effect element, a magnetoresistive element
Implementation Method 3
Some sensors include one or more electromagnetic flux sensing elements, such as a receiving coil to sense an electromagnetic flux
Data Source
AI summary
An apparatus, comprising: a substrate; a switching device that is formed over the substrate, the switching device including a gate layer, a source layer, and a drain layer; a first layer of dielectric material that is formed over the switching device; a first contact member that is electrically coupled to one of the gate layer, the source layer, and the drain layer, the first contact member being formed of at least one electrically-conductive material, the first contact member extending through the first layer of dielectric material; a plurality of first magnetic field sensing elements, the plurality of first magnetic field sensing elements being arranged to at least partially surround the first contact member, the plurality of first magnetic field sensing elements being arranged, at least in part, to form a sensing circuit for measuring a level of electrical current through the first contact member.