Impedance Normal Matching Cell Geometry for Calibration
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Solution Overview
Problem
Existing impedance normals are not suitable for calibrating low-impedance test units, such as battery cells in motor vehicles, as their measurement results are dependent on cable routing and connection position, leading to inconsistent results above 10 Hz.
Innovation Solution
Designing the impedance normal to match the connection arrangement of the cell being measured, allowing it to be connected in the same configuration as the cell, thereby reducing wiring dependence and enabling accurate impedance measurement across an extended frequency range by using an impedance normal with matching geometric and spatial arrangements of connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an impedance normal with arbitrary geometric design is used for calibration, then the calibration can be performed with standard components, but the measurement results become dependent on cable routing and connection position, leading to inconsistent results above 10 Hz
Solution Approach 1:
The impedance normal is designed to replicate the exact geometric and spatial connection arrangement of the cell to be measured. This copying approach ensures that the calibration conditions match the actual measurement conditions, eliminating errors caused by differences in cable routing and connection positions. The impedance normal includes connection contacts arranged identical to the cell's terminal structure, allowing frequency-dependent impedance measurements above 10 Hz to be calibrated accurately.
2Device complexity
If the impedance normal connections do not match the cell connection arrangement, then the impedance normal can be designed simply, but the calibration results cannot be used for frequencies above 10 Hz due to wiring dependence
Solution Approach 1:
The invention changes the geometric parameters of the impedance normal, specifically the spatial arrangement and positions of connection contacts, to match those of the cell. This parameter matching enables the impedance normal to accurately represent the electrical characteristics of the cell across the full frequency range from DC to above 10 Hz, making the calibration results applicable and meaningful for high-frequency impedance measurements.
Data Source
AI summary
A calibration method includes (a) connecting a impedance measuring device to an impedance standard which has at least two excitation terminals for feeding an excitation signal and two measuring terminals for determining a measurement signal, and which has a fixed or adjustable impedance which corresponds to the impedance target; (b) applying a voltage signal to the excitation terminals and measuring the current flowing through the impedance standard due to the voltage signal at the measuring terminals; or supplying a current signal to the excitation terminals and measuring the dropping voltage at the measuring terminals; and (c) calibrating the impedance measuring device against the impedance standard to the impedance target. The geometrical arrangement of terminals of the impedance standard corresponds to the geometrical arrangement of the terminals of the cell of which the impedance is to be measured.