Probe Assembly Minimizing Excitation Pick-Up Voltages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional battery impedance measurement methods suffer from excitation pick-up voltages due to loop geometries in the measurement setup, leading to errors in determining internal battery cell impedance without disconnecting the battery from the system.
Innovation Solution
A probe assembly with a cable assembly that constrains at least three wires close to each other to minimize loop formation, using bypass wires to eliminate induced voltages, ensuring the voltage sensing device measures only the actual voltage across the battery cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional two-probe measurement with separated cables is used, then the measurement setup is simple and easy to operate, but excitation pick-up voltages are induced in the wires leading to measurement errors
Solution Approach 1:
The cable assembly is segmented into multiple functionally distinct wire groups: current source wires (carrying excitation current), voltage sensing wires (measuring battery voltage), and bypass wires (providing alternative current paths). This segmentation allows each wire group to be optimized for its specific function, preventing excitation pick-up in voltage sensing wires while maintaining measurement accuracy.
Solution Approach 2:
Bypass wires act as intermediary elements that provide alternative current paths around the voltage sensing wires. By routing current through these bypass wires instead of through the voltage sensing wires, the invention eliminates induced voltages in the sensing circuit while maintaining the integrity of the measurement setup.
2Measurement precision
If Kelvin connections with separate contacts are used, then loading current flows almost entirely through the battery cell being measured, but loop geometries create unpredictable excitation voltages
Solution Approach 1:
The cable assembly is designed to create equipotential regions around the battery terminals by strategically routing wires and using bypass paths. This ensures that voltage sensing wires measure the true battery terminal voltage without picking up additional induced voltages from current-carrying wires, achieving equipotential conditions that eliminate measurement errors.
Solution Approach 2:
The invention converts the harmful effect of magnetic field induction into a beneficial arrangement by deliberately designing the cable geometry and bypass paths to channel induced voltages away from the measurement circuit. The bypass wires provide controlled paths for induced currents that do not interfere with voltage sensing, transforming the unavoidable magnetic induction into a non-interfering condition.
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 effectively minimizes excitation pick-up voltages, allowing for accurate measurement of internal battery cell impedance without disconnecting the battery from the system, reducing measurement errors caused by varying loop geometries.
Implementation Method 1
Faraday's law states that if a coil of N turns is placed in a region of changing flux (φ), a voltage (vi) will be induced across the coil according to equation (1): vi=N(dφ/dt)
Implementation Method 2
The current passing through the wires going to the current source 14 produces a magnetic field in the formed coil
Data Source
AI summary
A probe assembly for use with a battery impedance meter which minimizes excitation pick-up voltages by routing the wires from the meter to the battery cell terminals without forming a loop within a changing magnetic field caused by current drawn from the battery cell.