Battery State of Health Determination via Square Wave Pseudo-Impedance
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Solution Overview
Problem
Conventional methods for determining battery state of health require high-performance CPUs and significant computational resources due to the need for trigonometric functions, leading to high operational and processing loads.
Innovation Solution
The method involves causing the battery to discharge square wave pulses, sampling response voltages, expanding them into orthogonal square wave components, and calculating pseudo-impedance to determine battery health, eliminating the need for trigonometric operations and reducing CPU load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Fourier transformation with trigonometric functions is used to calculate internal impedance, then measurement precision is improved, but device complexity and operational load increase
Solution Approach 1:
The patent extracts only the essential impedance information from the voltage response waveform without performing complete Fourier transformation. By using maximum likelihood estimation to directly calculate impedance parameters from the sampled voltage data, it extracts the needed measurement information while eliminating complex trigonometric computations, thus reducing CPU requirements while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical computation process of Fourier transformation with a mathematical estimation approach. Instead of using CPU-intensive trigonometric functions, it employs maximum likelihood estimation algorithms that compute impedance parameters through simpler iterative calculations, substituting a computationally heavy mechanical process with a more efficient mathematical method.
2Measurement precision
If sine wave alternative current is applied to measure internal impedance, then measurement precision is improved, but equipment size and cost increase
Solution Approach 1:
The patent enables the battery to serve its own measurement function by using its normal discharge process as the measurement stimulus. Instead of requiring external sine wave generation equipment, the system uses the battery's own discharge current waveform to excite the system and measures the voltage response, allowing the battery to self-diagnose its impedance characteristics without additional measurement equipment.
Solution Approach 2:
The patent makes the battery discharge process serve dual purposes: normal power delivery and impedance measurement. The discharge circuit performs both energy delivery and measurement excitation functions simultaneously, eliminating the need for separate measurement equipment and enabling multi-functionality in the battery system.
3Device complexity
If pulse discharge with Fourier transformation is used, then equipment downsizing is achieved, but operational load remains high
Solution Approach 1:
The patent extracts essential impedance information from pulse discharge data without performing complete Fourier transformation. By using maximum likelihood estimation to directly compute impedance parameters from the voltage response during pulse discharge, it extracts the necessary measurement information while eliminating computationally intensive trigonometric operations, thus reducing CPU operational load while maintaining equipment downsizing benefits.
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 allows for precise determination of battery state of health with significantly reduced operational and processing loads, enabling the use of lower-function CPUs and reducing costs, while maintaining precision comparable to methods using true impedance.
Implementation Method 1
causing the battery to discharge square wave pulses with a prescribed cycle at a prescribed current value
Implementation Method 2
expanding sampled response voltages into orthogonal square wave components
Implementation Method 3
expanding sampled response voltages into orthogonal square wave components
Implementation Method 4
calculating a coefficient a1 in the fundamental frequency by comparing the fundamental square wave component of the response voltage with a basis square wave
Implementation Method 5
dividing an amplitude of the square wave component by the current value of the pulse-discharge to obtain a pseudo-impedance
Data Source
AI summary
The method and the device for determining state of health of the battery, in addition to the power supply system using the device, which can remarkably reduce operational and processing load by expanding the data sampled at the time when the battery is caused to discharge square wave pulses into the square wave is provided. The method of the invention for determining state of health of a battery comprising the steps of: causing the battery to discharge square wave pulses with a prescribed cycle at a prescribed current value; sampling response voltages at a time of a pulse-discharge; expanding sampled response voltages into orthogonal square wave components; dividing an amplitude of the square wave component by the current value of the pulse-discharge to obtain a pseudo-impedance; and determining state of health of the battery based on the pseudo-impedance.