Battery Fuel Gauge Using Polynomial Model for SoC Estimation
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Solution Overview
Problem
Conventional systems for determining battery state of charge (SoC) are computationally and memory-intensive, making them unsuitable for contemporary mobile electronic devices due to the complex interplay of factors affecting battery performance, such as temperature, age, and load conditions.
Innovation Solution
A system utilizing a battery model that includes a current sensor, voltage sensor, and temperature sensor, which uses a resistive component updated by current and voltage measurements to estimate battery SoC, simplifying the model to reduce memory requirements by approximating nonlinear relationships with polynomial functions and updating Rseries values based on specific criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional computational systems are used to determine battery SoC, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transforms the complex computational problem into a simplified parameter-based solution by using polynomial functions to model the relationship between open-circuit voltage and state of charge. This approach changes the parameters from complex multi-factor computations to straightforward polynomial evaluations, maintaining accuracy while reducing computational complexity.
Solution Approach 2:
The patent extracts and separates the dominant factors affecting battery SoC from the complex interplay of all variables. By identifying and modeling only the most significant relationships (particularly the OCV-SoC relationship through polynomials), the system removes unnecessary computational complexity while preserving essential measurement precision.
2Measurement precision
If conventional computational systems are used to determine battery SoC, then measurement precision is improved, but memory usage increases
Solution Approach 1:
The patent reduces memory requirements by changing from storing complex computational models and large datasets to storing simple polynomial coefficients. This parameter transformation allows the system to maintain high measurement precision while using minimal memory resources suitable for mobile devices.
Solution Approach 2:
The patent employs lightweight polynomial functions that require minimal computational resources and memory, analogous to using simple, disposable solutions rather than complex, resource-intensive systems. This approach provides sufficient accuracy for practical purposes while dramatically reducing memory consumption.
3Measurement precision
If detailed battery models are used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent transforms complex battery modeling operations into simple polynomial evaluations that are computationally efficient and easy to implement. By changing the mathematical representation from complex differential equations to polynomial functions, the system maintains measurement precision while dramatically improving ease of operation and computational speed.
Data Source
AI summary
A system for estimating battery state of charge (SoC) includes evaluating a battery model to produce an estimated battery voltage using a previously produced SoC. Current and voltage measurements are combined with the estimated battery voltage to produce a present battery SoC. The battery model may be updated by taking battery measurements when certain conditions occur.