Battery Pack Power Limit Calculation Using OCV and DCIR Tables
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Solution Overview
Problem
Current electrochemical-based battery models for calculating the maximum power limit of a battery pack require significant computing resources and memory, making them inefficient for real-time applications in electric vehicles.
Innovation Solution
A system comprising one or more controllers in electronic communication with the battery pack, utilizing battery open circuit voltage and direct current internal resistance look-up tables to calculate the maximum power limit based on discharge current, state-of-charge, and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrochemical-based battery models are used to calculate maximum power limit, then calculation accuracy is improved, but computing resources and memory requirements increase significantly
Solution Approach 1:
The patent divides the complex electrochemical battery model into multiple simplified lookup tables (OCV vs. SOC tables, DCIR vs. SOC tables at different temperatures and current rates). Each table stores pre-calculated values for specific conditions, allowing the system to retrieve approximate values quickly without performing complex real-time electrochemical calculations. This segmentation maintains acceptable accuracy while dramatically reducing computational burden.
Solution Approach 2:
The patent creates simplified copies of the electrochemical model in the form of lookup tables that approximate the complex relationships between battery parameters. Instead of implementing the full electrochemical model, the system uses tabulated data that replicates the essential behavior of the battery under various conditions, enabling fast calculations with minimal memory usage.
2Productivity
If real-time power management is implemented, then battery performance optimization is improved, but computational processing time increases
Solution Approach 1:
The patent performs preliminary calculations by pre-computing open circuit voltage and DCIR values for various battery states and storing them in lookup tables before runtime. During real-time operation, the controller only needs to retrieve pre-calculated values based on current SOC and temperature readings, then apply simple formulas to determine maximum power limits. This eliminates the need for complex real-time electrochemical simulations while maintaining the ability to optimize battery performance dynamically.
Data Source
AI summary
A system for calculating the maximum power limit of a battery pack for an electric vehicle includes one or more controllers in electronic communication with the battery pack. A plurality of battery open circuit voltage look-up tables and a plurality of direct current internal resistance (DCIR) look-up tables are stored in memory of the one or more controllers.