Battery Pack Current Limits Using High-Risk Cell Voltage Change
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Solution Overview
Problem
In battery management systems, existing methods fail to accurately identify and manage high-risk battery cells that may exceed operating voltage limits, leading to inefficient battery pack performance and stability issues, particularly in electric vehicles with varying battery cell states.
Innovation Solution
A battery management system that calculates state information for each battery cell, selects high-risk cells based on maximum voltage change amounts, and sets current limit values to prevent voltage range violations, using specific threshold values and polarization voltages to optimize charging and discharging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If representative values (average voltage, internal resistance, capacity) are used to estimate battery state, then device complexity is reduced and ease of operation is improved, but measurement precision deteriorates and reliability worsens due to cell variations
Solution Approach 1:
The patent segments the battery pack into individual battery cells and further divides them into groups based on their state characteristics. Instead of treating the battery pack as a single unit represented by average values, the system monitors each cell individually and categorizes them into first groups (cells close to voltage limits) and second groups (cells within safe margins). This segmentation enables precise tracking of cell variations while maintaining manageable system complexity through group-based management.
Solution Approach 2:
The patent introduces a new dimension of analysis by classifying battery cells into multiple groups based on their proximity to voltage limits and state of charge levels. This group-based classification adds a categorical dimension to the traditional single-value battery state estimation, allowing the system to capture the distribution and variation of cell states without requiring complex individual monitoring of all parameters for every cell.
2Reliability
If individual battery cell states are monitored to prevent voltage limit violations, then reliability is improved and measurement precision is enhanced, but device complexity increases and productivity decreases
Solution Approach 1:
The patent segments battery cells into management groups based on their state characteristics, particularly their proximity to voltage limits and state of charge levels. By dividing cells into first groups (requiring closer monitoring) and second groups (within safe margins), the system achieves reliable individual cell monitoring while reducing complexity through group-based management strategies rather than uniform monitoring of all cells.
Solution Approach 2:
The patent applies local quality by differentiating monitoring and control strategies for different cell groups. First group cells, which are closer to voltage limits or have higher state of charge, receive more intensive monitoring and stricter current limiting. Second group cells, which are within safe margins, receive standard monitoring. This localized approach ensures reliability for critical cells while reducing overall system complexity.
3Ease of operation
If current is limited based on representative battery values, then ease of operation is maintained, but productivity decreases and reliability worsens due to inaccurate current limit calculation
Solution Approach 1:
The patent segments battery cells into groups based on their state of charge and proximity to voltage limits. The current limiting strategy is then applied differently to each group: first group cells (closer to limits) receive stricter current limits, while second group cells (within margins) receive more permissive limits. This segmented approach maintains ease of operation through automated group-based control while improving productivity by allowing higher overall current throughput compared to uniform conservative limiting.
Solution Approach 2:
The patent applies local quality by implementing differentiated current limiting for different cell groups. Instead of applying a single conservative current limit to the entire battery pack based on representative values, the system calculates and applies tailored current limits to each group based on their specific state. This enables more aggressive and efficient charging/discharging for cells within safe margins while maintaining safety for cells closer to limits.
4Reliability
If conservative current limits are applied to all cells, then reliability is improved by preventing voltage limit violations, but productivity decreases due to underutilization of battery capacity
Solution Approach 1:
The patent segments battery cells into first groups (closer to voltage limits or with higher state of charge) and second groups (within safe margins). Current limiting is applied selectively: stricter limits for first group cells to ensure reliability, and more permissive limits for second group cells to maximize productivity. This segmentation enables the system to prevent voltage limit violations for critical cells while fully utilizing the capacity of cells within safe margins.
Solution Approach 2:
The patent applies local quality by implementing differentiated current limiting strategies for different cell groups. First group cells receive conservative current limits to maintain reliability and prevent voltage limit violations. Second group cells receive optimized current limits that allow higher throughput while remaining within safe operating margins. This localized approach achieves both reliability for critical cells and productivity for the overall battery pack.
Data Source
AI summary
Provided is a battery management system and method for selecting at least one battery cell of a high-risk group and calculating a maximum current limit value for stably using a battery pack using the selected at least one battery cell of the high-risk group. According to the present invention, the battery cells of high-risk group may be selected and managed by calculating a maximum voltage change amount of a plurality of battery cells, and the battery pack may be stably used by calculating a maximum current limit value that prevents the battery cell from being out of an operating voltage range to have a maximum margin.