Battery Pack Equalization Using Predicted State-of-Charge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Battery packs in electric vehicles face performance limitations due to differing total capacities and self-discharge rates of individual cells, leading to unnecessary energy wastage and reduced battery life, as current equalization methods rely on voltage comparisons rather than predictive analysis.
Innovation Solution
A method and system that computes an equalization metric based on total capacity and state-of-charge estimates to determine which cells need bucking or boosting during the charging process, optimizing energy usage and extending battery life by predicting which cells will limit pack performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery cells are equalized using voltage comparison during charging, then battery pack performance is improved, but energy is needlessly wasted due to bucking or boosting the wrong cells
Solution Approach 1:
The system performs preliminary prediction of which battery cells will limit pack performance before the charging process completes. By computing predicted end-of-charge state-of-charge values and comparing them against target values, the system identifies cells that will need equalization in advance, allowing for optimized equalization actions that prevent energy waste from incorrect equalization decisions.
Solution Approach 2:
The system uses feedback from predicted end-of-charge state-of-charge values to adjust equalization decisions during the charging process. By continuously monitoring predicted SOC values and comparing them with target SOC values, the system provides feedback to determine which cells require bucking or boosting, ensuring accurate equalization while minimizing energy waste.
2Quantity of substance
If battery cells are equalized during charging, then energy storage capacity is maximized, but heat generation increases requiring thermal management
Solution Approach 1:
The system performs equalization predictions and planning during the charging process before the battery pack is disconnected. By identifying which cells need equalization in advance based on predicted end-of-charge SOC values, the system can execute equalization actions optimally, minimizing unnecessary equalization operations and thereby reducing heat generation and thermal management requirements.
3Quantity of substance
If battery cells have differing total capacities, then battery pack energy storage is limited by the weakest cell, but equalization operations increase system complexity
Solution Approach 1:
The system uses feedback from predicted end-of-charge state-of-charge values to identify which specific cells require equalization. By comparing predicted SOC values against target SOC values, the system determines equalization needs based on actual cell performance rather than uniform treatment, optimizing energy storage while managing system complexity through intelligent decision-making.
Solution Approach 2:
The system changes the parameter used for equalization decisions from simple voltage comparison to predicted state-of-charge values. This parameter change allows the system to account for differing cell capacities and aging characteristics, enabling more accurate equalization decisions that maximize energy storage while adapting to varying cell conditions.
Data Source
AI summary
A system and method for equalizing a battery pack during a battery pack charging process in accordance with an exemplary embodiment is provided. The method includes receiving total capacity estimates for all battery cells in the battery pack, and receiving state-of-charge estimates for all battery cells in the battery pack. The method further includes computing an equalization metric for all battery cells in the battery pack. The method further includes determining an equalization action for all battery cells in the battery pack, and initiating that equalization action. The method further includes executing a battery pack charging step.