Dynamic SOC Window Adjustment for Battery Cycle Life
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Solution Overview
Problem
Lithium-ion battery packs in automotive applications face challenges in accurately estimating remaining capacity and extending cycle life, as existing methods are inaccurate and can shorten battery life, particularly due to high charge levels, elevated temperatures, and extreme load conditions, leading to uneven capacity degradation and user perception of inferior battery performance.
Innovation Solution
A management system that determines an adjustable charge profile for lithium-ion battery packs, incorporating operational parameters to set state of charge (SOC) windows and energy transfer stages, allowing for optimized drive range modes that balance battery longevity with user requirements, thereby adapting to capacity decreases over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery is charged to high charge levels to extend driving range, then the vehicle range is improved, but the battery cycle life is shortened
Solution Approach 1:
The patent implements dynamic adjustment of the maximum charge SOC limit based on battery age. The charge profile manager modifies the charge profile to limit the maximum charge SOC to a value less than 100% when the battery has undergone a number of charge cycles greater than a threshold value. This dynamic adaptation allows the system to extend vehicle range when the battery is new while protecting cycle life as the battery ages.
Solution Approach 2:
The system changes the charge profile parameter (maximum charge SOC limit) based on battery age and charge cycle history. By adjusting this parameter dynamically, the system optimizes the trade-off between vehicle range and battery cycle life, preventing capacity degradation while maintaining acceptable range for the battery's current state.
2Measurement precision
If deep discharge is used to accurately measure battery capacity, then measurement precision is improved, but battery lifetime is dramatically shortened
Solution Approach 1:
The system performs preliminary characterization of the battery pack's charge capacity during manufacturing or initial use. This preliminary action establishes a baseline capacity measurement without requiring deep discharge, and subsequent capacity estimates are derived from this baseline combined with monitoring of charge cycle history and battery age.
Solution Approach 2:
The battery management system continuously monitors charge cycle history, battery age, and operational conditions to self-adjust capacity estimates. This self-service approach eliminates the need for periodic deep discharge tests, as the system maintains accurate capacity knowledge through continuous monitoring and modeling of battery degradation.
3Duration of action of stationary object
If the maximum charge SOC limit is reduced to extend battery life, then battery cycle life is improved, but the available driving range is reduced
Solution Approach 1:
The system dynamically adjusts the maximum charge SOC limit based on battery age and charge cycle count. When the battery is new, the system allows higher charge levels to maximize range. As the battery ages and exceeds the charge cycle threshold, the system automatically reduces the maximum charge SOC limit to protect cycle life, creating a dynamic balance between range and longevity.
Data Source
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AI summary
A management system for a battery cell pack, the management system including a controller determining an adjustable charge profile for the battery cell pack wherein the adjustable charge profile includes an operational parameter identifying a next operation drive range mode from a set of drive range modes for the battery cell pack wherein each the drive range mode includes a state of charge (SOC) window between a charge SOC and a discharge SOC, with the set of drive range modes including a first drive range mode having a first SOC window and including a second drive range mode having a second SOC window less than the first SOC window; and one or more energy transfer stages to produce the charge SOC of the next operation drive range mode in the battery cell pack.