Battery SOC Estimation Using Segmented Lookup Tables
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Solution Overview
Problem
Existing battery state-of-charge (SOC) estimation methods require significant computational resources and memory, making them costly and inefficient for use in battery management systems, particularly in hybrid electric vehicles where precise SOC estimation is crucial to prevent overcharging and over-discharging.
Innovation Solution
A battery SOC estimation method that divides the two-dimensional coordinate system representing the relation between battery open-circuit voltages and SOCs into multiple steps, using a small-capacity memory and inexpensive processor to calculate and display the SOC by applying function information from an SOC table, and a battery management system comprising a sensing resistor, control switch unit, and processor to generate control signals and calculate parameters for the battery equivalent model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing battery SOC estimation methods are used, then measurement precision is improved, but device complexity and cost increase due to requiring significant computational resources and memory
Solution Approach 1:
The patent divides the two-dimensional coordinate system representing the relationship between battery open-circuit voltages and SOCs into multiple discrete steps. This segmentation allows the system to use simplified function information stored in tables rather than requiring complex continuous calculations, thereby reducing computational resource requirements while maintaining acceptable estimation accuracy.
Solution Approach 2:
The patent creates lookup tables that store pre-calculated function information representing the voltage-SOC relationship at different temperatures. Instead of performing complex real-time calculations, the system copies and retrieves relevant data from these tables, significantly reducing the computational burden on the processor and memory while preserving measurement precision.
2Measurement precision
If existing battery SOC estimation methods are used, then measurement precision is improved, but manufacturing cost increases due to requiring expensive processors and large-capacity memory
Solution Approach 1:
By segmenting the coordinate system into discrete steps and storing function information in lookup tables, the patent eliminates the need for expensive high-performance processors and large memory capacities. This approach allows the system to be manufactured using inexpensive components while maintaining acceptable SOC estimation accuracy.
Solution Approach 2:
The patent replaces expensive computational resources with inexpensive lookup tables that can be stored in small-capacity memory. The system uses simple retrieval operations instead of complex calculations, enabling the use of low-cost processors and reducing overall manufacturing costs while maintaining functional performance.
3Device complexity
If the coordinate system is divided into multiple steps with function information stored in tables, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent incorporates temperature as a dynamic variable that affects the voltage-SOC relationship. By storing function information at multiple temperature levels in the lookup tables and selecting the appropriate table based on current temperature conditions, the system maintains measurement precision across varying operating conditions while using simple retrieval operations instead of complex calculations.
Data Source
AI summary
Provided are a battery state-of-charge (SOC) estimation method and a battery management system which are capable of estimating an SOC using an inexpensive processor and a small-capacity memory. The SOC estimation method includes an SOC table creation step, an SOC calculation step, an SOC comparison step, and a processing step. The battery management system includes a battery, a sensing resistor, a control switch unit, and a processor.