Battery BMS SOC Window Control for Longer Cycle Life
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Solution Overview
Problem
The cycle-life of lithium-ion batteries in electric vehicles is shortened due to frequent and rapid charging, leading to increased replacement costs and environmental impact, necessitating a method to extend battery life based on usage patterns.
Innovation Solution
A battery management system (BMS) controls charging based on eco-friendly and normal modes, using different state of charge (SOC) limits and charging methods to reduce rapid charging and extend battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid charging method is used to reduce charging time, then charging speed is improved, but battery cycle-life is shortened
Solution Approach 1:
The patent applies dynamics by making the charging control strategy adaptable and changeable based on real-time conditions. The BMS dynamically adjusts charging parameters including SOC limits, charging current, and voltage thresholds according to battery state, temperature, and charging stage, transforming a static charging process into a dynamic one that optimizes both speed and battery longevity
Solution Approach 2:
The patent implements parameter changes by modifying multiple charging parameters simultaneously: adjusting SOC upper/lower limits based on temperature and charging stage, varying charging current thresholds (e.g., 0.5C, 0.2C, 0.05C for different stages), and changing voltage thresholds. These parameter adjustments enable the system to switch between rapid and slow charging modes appropriately
2Use of energy by moving object
If battery capacity utilization is increased to improve energy efficiency, then energy efficiency is improved, but battery aging is accelerated
Solution Approach 1:
The patent applies partial action by intentionally not utilizing the full battery capacity range. The BMS sets dynamic SOC upper limits (e.g., 90%, 80%, 70% depending on temperature and charging stage) that are lower than the maximum capacity, and maintains higher SOC lower limits, thereby using only a partial range of battery capacity to reduce stress and aging while maintaining sufficient energy efficiency for daily use
3Device complexity
If charging control is simplified to reduce system complexity, then system complexity is reduced, but charging optimization capability is diminished
Solution Approach 1:
The patent applies segmentation by dividing the charging process into multiple distinct stages (first charging stage with high current threshold 0.5C, second stage with medium threshold 0.2C, third stage with low threshold 0.05C). Each stage has its own SOC limits, current thresholds, and control strategies, allowing complex optimization to be achieved through manageable segmented control rather than a monolithic complex system
Data Source
AI summary
A battery system includes: a battery and a battery management system (BMS) for controlling charging of the battery depending on a normal mode using a first battery capacity between a first lower limit state of charge (SOC) and a first upper limit SOC or an eco-friendly mode using a second battery capacity between a second lower limit SOC and a second upper limit SOC, the first lower limit SOC is smaller than the second lower limit SOC, and the first upper limit SOC is greater than the second upper limit SOC.