Battery Impedance Measurement Using Sum-of-Sinusoids Signal
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Solution Overview
Problem
Existing impedance measurement systems have limited resolution for batteries with low internal impedance, making it difficult to accurately assess their health, and are slow due to methods like electrochemical impedance spectroscopy, which requires time-consuming measurements.
Innovation Solution
An impedance measurement device using a Sum-of-Sinusoids (SOS) signal to simultaneously test batteries at multiple frequencies, allowing for real-time impedance spectrum measurement with improved resolution and speed, incorporating a processor, data acquisition system, SOS generator, preamplifier, and power supply to calculate impedance by dividing measured voltage by current response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrochemical impedance spectroscopy is used to achieve high resolution impedance measurement, then measurement precision is improved, but measurement time increases significantly
Solution Approach 1:
The patent divides the impedance measurement into multiple frequency points that are measured simultaneously using parallel signal injection circuits. Each frequency point has its own injection circuit and measurement channel, allowing concurrent measurement rather than sequential scanning, thus reducing total measurement time while maintaining precision across all frequency points
Solution Approach 2:
The patent combines multiple impedance measurement channels into a single integrated system where multiple frequency signals are injected simultaneously through parallel circuits. The system merges the measurement results from all frequency points to generate a complete impedance spectrum, achieving both high resolution and rapid measurement
2Measurement precision
If existing impedance measurement systems operate at 500 mA excitation current, then they can measure batteries with 10 mOhm impedance adequately, but they lack resolution for batteries with lower impedance (e.g., 1 mOhm)
Solution Approach 1:
The patent implements dynamic adjustment of excitation current amplitude based on the impedance magnitude of the battery being measured. The system automatically adapts the current level to match the specific battery characteristics, enabling high-resolution measurement across a wide range of impedance values from 1 mOhm to 10 mOhm and beyond
Solution Approach 2:
The patent changes the excitation current parameter dynamically to optimize measurement resolution for different battery types. By adjusting the current amplitude according to the battery's impedance level, the system maintains adequate signal-to-noise ratio and measurement precision whether measuring low-impedance (1 mOhm) or higher-impedance (10 mOhm) batteries
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, rapid assessment of battery health with improved resolution, capable of measuring low impedance batteries with high precision and reducing measurement time significantly compared to conventional methods.
Implementation Method 1
A signal generator is used to apply an AC signal across the test battery
Implementation Method 2
measurements of the frequency response of the impedance of the test battery
Data Source
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AI summary
Battery impedance testing devices, circuits, systems, and related methods are disclosed. An impedance measurement device includes a current driver configured to generate an excitation current signal to be applied to a test battery responsive to a control signal, and a processor operably coupled with the current driver. The processor is configured to generate the control signal during an auto ranging mode and a measuring mode. The auto ranging mode applies the excitation current signal to the test battery over a plurality of different amplitudes to measure a response to the excitation current signal at each amplitude. The measuring mode applies the excitation current signal to the test battery for an amplitude responsive to the results of the auto ranging mode. Improved sensitivity and resolution may be achieved for low impedance batteries with a rapid measurement time.