Busbar Sensor Assembly for Coreless Motor Current Measurement
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Solution Overview
Problem
Existing methods for determining electric current in electric drive motors of motor vehicles require large, heavy metal cores for magnetic field measurement, leading to high structural space and material costs.
Innovation Solution
A compact and cost-effective sensor assembly using two perpendicular magnetic field sensors attached symmetrically to a busbar, eliminating the need for a magnetic core, with integrated circuits for differential evaluation and processing of magnetic fields, and a thermoplastic cover for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal core is used to shape and collect magnetic field lines for current measurement, then measurement accuracy is improved, but device weight and structural space increase
Solution Approach 1:
The invention extracts and eliminates the metal core component from the sensor assembly. By using two magnetic field sensors positioned symmetrically on opposite sides of the busbar, the system measures the magnetic field difference without requiring a metal core to shape or collect magnetic field lines, thereby reducing weight while maintaining measurement capability
Solution Approach 2:
The invention introduces an intermediary measurement approach where two magnetic field sensors are positioned symmetrically around the busbar. Instead of using a metal core to concentrate the magnetic field, the system uses the spatial arrangement of sensors to detect the magnetic field difference, with the busbar itself serving as the reference for symmetric positioning
2Measurement precision
If a metal core is used to shape and collect magnetic field lines for current measurement, then measurement accuracy is improved, but device complexity and material costs increase
Solution Approach 1:
The invention removes the complex metal core structure and associated shaping requirements. The simplified design uses only two magnetic field sensors mounted symmetrically on the busbar, eliminating the need for core fabrication, assembly, and alignment procedures
Solution Approach 2:
The busbar serves a dual function: it conducts electrical current and provides the structural reference for symmetric sensor mounting. The geometry of the busbar itself defines the positioning locations for the sensors, eliminating the need for separate core components to establish the measurement geometry
3Measurement precision
If a metal core is used to shape and collect magnetic field lines for current measurement, then magnetic field concentration is improved, but manufacturing costs increase
Solution Approach 1:
The invention extracts the metal core component entirely from the manufacturing process. The sensor assembly is manufactured by simply mounting two magnetic field sensors at symmetric positions on the busbar, which can be done using standard mounting techniques without specialized core fabrication or assembly procedures
Solution Approach 2:
The invention replaces the expensive, precision-fabricated metal core with inexpensive magnetic field sensors that can be mounted using standard, low-cost techniques. The symmetric positioning on the busbar provides sufficient measurement accuracy without requiring precision-engineered core components
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
Enables accurate and efficient determination of electric current with reduced space and material requirements, minimizing measurement errors and costs while withstanding environmental influences.
Implementation Method 1
A flowing current induces in the region of the busbar a magnetic field with field lines which run perpendicularly to the direction of extent of the busbar or to the direction of flow of the electric current
Implementation Method 2
The magnetic field sensors are comprised of an integrated circuit (IC)... The IC can be robust with respect to environmental influences in the region of a motor vehicle by virtue of conventional encapsulation in a semiconductor housing
Data Source
AI summary
A sensor assembly for the determination of an electric current which flows through an electric drive machine of a motor vehicle comprises a busbar through which the electric current flows, and a first and a second magnetic field sensor for determining magnetic fields in the region of the busbar, wherein the magnetic field sensors are attached so that they are spaced apart from one another in a direction perpendicular to the direction of extent of the busbar.