Measuring Resistor with Multiple Voltage Contacts
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Solution Overview
Problem
Current low-resistance current sense resistors suffer from measurement inaccuracies due to inhomogeneous current density and orientation, caused by asymmetric current input, lead inhomogeneities, temperature dependencies, skin effect, and magnetic-field effects, which introduce errors when calculating electric current using Ohm's law.
Innovation Solution
The solution involves a measuring resistor with multiple pairs of voltage-measuring contacts arranged to measure the voltage drop across the resistor element at different spatial positions, allowing for correction of inhomogeneities in current density through averaging, and using a conductive material with low resistivity for connection parts and a low-resistance resistive material for the resistor element, along with a calibration process to determine optimal weighting factors for measurement parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pair of voltage-measuring contacts is used to measure the voltage drop across the resistor element, then the device complexity is reduced, but the measurement precision deteriorates due to inhomogeneous current density and orientation
Solution Approach 1:
The voltage measurement function is segmented into multiple independent measurement channels, each with its own pair of voltage-measuring contacts positioned at different locations on the resistor element. This allows the system to capture spatial variations in current density by measuring voltage drops at multiple positions simultaneously, thereby improving measurement precision while accepting increased device complexity
Solution Approach 2:
The invention changes the measurement parameter from a single voltage value to multiple voltage values at different spatial positions. By measuring voltage drops at multiple locations and processing these values (e.g., through averaging or weighted combinations), the system compensates for inhomogeneous current density and orientation effects, improving measurement precision
2Measurement precision
If the resistor element width is increased to reduce resistance, then the current density becomes more inhomogeneous, but the measurement accuracy can be improved through multiple measurement positions
Solution Approach 1:
Multiple pairs of voltage-measuring contacts are positioned at different spatial locations across the resistor element width. This segmentation of measurement positions allows the system to capture and account for current density variations across the expanded resistor width, enabling accurate measurements even when the resistor element is wide to achieve low resistance
Solution Approach 2:
Each pair of voltage-measuring contacts measures the voltage drop at its specific local position on the resistor element. By having multiple measurement pairs at different locations, the system captures local variations in current density and orientation, allowing for compensated calculation of the overall voltage drop across the resistor element
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
This approach enables more precise current measurement by accounting for spatial variations in current density, allowing for larger resistor widths and improved accuracy across varying measurement conditions, including external magnetic fields, thereby reducing measurement noise and increasing resolution.
Implementation Method 1
the voltage drop across the resistor element of the low-resistance current sense resistor is measured. According to Ohm's law, the measured voltage is then a measure of the electric current flowing through the current sense resistor
Implementation Method 2
two connection parts made of an electrically conductive conducting material in order to conduct the electric current into and out of the resistor
Implementation Method 3
Two thermally conductive elements, which are likewise planar and may be made of copper, for example, and are used solely for buffering and dissipating generated heat
Data Source
AI summary
The invention relates to a measuring resistor (1), in particular a low-resistance current-measuring resistor, comprising two terminal parts (2, 3) that consist of a conductor material for introducing and discharging a current, and a resistor element (4) that consists of a resistor material, wherein the resistor element (4) is arranged between the two terminal parts (2, 3) in the direction of the current and current flows through the resistor element (4). According to one variant of the invention, the measuring resistor (1) has several pairs of voltage-measuring contacts (7) for measuring the voltage falling across the resistor element (4) in order to be able to compensate metrologically for inhomogeneities in the current density. In contrast, according to another variant of the invention, one pair of voltage-measuring contacts (7) is arranged at a location at which the measuring resistor (1) exhibits neither a capacitive behavior nor an inductive behavior, such that the current flowing through the measuring resistor (1) and the voltage across the voltage-measuring contacts (7) are substantially in phase.