Battery Impedance Measurement Using Pseudo-Random Binary Sequences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring the impedance of energy storage elements in batteries are inefficient, particularly in on-board battery management systems and lightweight diagnostic tools, as they require lengthy spectrum scanning and are not suited for applying sinusoidal current variations, leading to suboptimal energy consumption and measurement accuracy.
Innovation Solution
A method and device that apply a non-binary sequence of current variations, obtained by convolving a pseudo-random binary sequence with coefficients of a finite impulse response filter, to measure impedance across a wide frequency band with approximately constant power levels within the band of interest and significant attenuation outside, enabling accurate and energy-efficient broadband impedance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spectrum scanning methods are used to measure impedance, then measurement accuracy can be achieved, but measurement time becomes excessively long
Solution Approach 1:
The patent combines multiple frequency point measurements into a single measurement by applying a pseudo-random binary sequence (PRBS) that contains multiple frequency components simultaneously. This allows impedance to be measured across a broad frequency spectrum in one go rather than scanning through frequencies sequentially, thereby reducing measurement time while maintaining accuracy through correlation-based analysis
Solution Approach 2:
The patent employs periodic pseudo-random binary sequences as excitation signals that repeat over time. These periodic sequences allow for efficient correlation-based measurement techniques where the impedance response can be extracted by correlating the voltage response with the known excitation sequence, enabling rapid broadband impedance characterization
2Measurement precision
If sinusoidal current variations are applied for impedance measurement, then accurate impedance data can be obtained, but energy consumption increases
Solution Approach 1:
The patent uses periodic pseudo-random binary sequences instead of continuous sinusoidal excitation. These sequences are applied in discrete bursts and allow for correlation-based measurement that extracts impedance information efficiently, reducing the total energy required compared to continuous sinusoidal sweeping while maintaining measurement accuracy
Solution Approach 2:
The patent changes the excitation signal parameters by using pseudo-random binary sequences with varying time constants and amplitude levels. This allows optimization of the excitation signal to achieve sufficient impedance measurement accuracy with lower energy consumption compared to traditional sinusoidal methods
3Adaptability or versatility
If broadband frequency measurement is implemented, then comprehensive impedance information is obtained, but measurement complexity increases
Solution Approach 1:
The patent introduces correlation analysis as an intermediary processing step that simplifies the measurement system. By correlating the voltage response with the known pseudo-random excitation sequence, the system can extract impedance information across broad frequency ranges without requiring complex multi-frequency measurement hardware, thus reducing overall system complexity
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a method for determining the impedance of an energy storage element (100) of an electric battery, comprising the following steps: applying a predetermined sequence of current variations to the element (100); measuring the voltage variations at the terminals of the element (100) in response to the application of said sequence; and determining the impedance of the element (100) from the measured voltage variations, wherein said sequence is a non-binary sequence produced by the convolution of a pseudo-random binary sequence with finite impulse response filter coefficients.