Battery Control Device Ion Concentration Unevenness Management
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Solution Overview
Problem
Existing battery systems for electrically powered vehicles face challenges in preventing high-rate deterioration of non-aqueous secondary batteries due to uneven ion concentration in the electrolyte, particularly during external charging, as existing methods fail to appropriately manage both charging and discharging restrictions.
Innovation Solution
A battery system that includes a control device to calculate separate integrated evaluation values for overdischarging and overcharging based on distinct threshold values and relaxation coefficients, allowing for dynamic adjustment of charging and discharging power to prevent excessive ion concentration unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single integrated evaluation value is used to determine both overdischarging and overcharging, then the control system is simple, but it cannot appropriately prevent high-rate deterioration during external charging
Solution Approach 1:
The patent divides the single integrated evaluation value into two separate evaluation values: one for overdischarging determination and another for overcharging determination. This segmentation allows each evaluation value to be optimized for its specific function, enabling appropriate prevention of high-rate deterioration during both vehicle operation and external charging without requiring overly complex control logic.
Solution Approach 2:
The patent applies different threshold values and relaxation coefficients to the two separate evaluation values based on their specific purposes. The overdischarging evaluation uses thresholds and relaxation parameters optimized for vehicle operation conditions, while the overcharging evaluation uses different parameters optimized for external charging conditions. This local customization of parameters ensures reliable deterioration prevention for each charging scenario.
2Device complexity
If threshold values for overdischarging and overcharging are set to the same absolute value, then the calculation is simplified, but it fails to account for different charging modes
Solution Approach 1:
The patent implements dynamic threshold values that change based on the charging mode. During vehicle operation, different threshold values are applied compared to external charging modes. This dynamic adjustment allows the system to adapt to different charging scenarios, preventing high-rate deterioration in each specific mode while maintaining manageable calculation complexity through systematic parameter management.
Solution Approach 2:
The patent changes key parameters including threshold values and relaxation coefficients based on the charging mode. By adjusting these parameters dynamically - using one set for vehicle operation and another set for external charging - the system achieves versatility across different charging modes without significantly increasing calculation complexity, as the parameter changes follow systematic rules.
3Device complexity
If relaxation coefficients are not differentiated between charging and discharging, then the integration process is simpler, but it cannot accurately sense overcharging and overdischarging
Solution Approach 1:
The patent applies different relaxation coefficients to the integration processes for overcharging and overdischarging evaluation. The relaxation coefficient for overdischarging is optimized to accurately detect ion concentration unevenness during vehicle operation, while a different coefficient is used for overcharging detection during external charging. This local optimization of coefficients enhances measurement precision for each specific condition without requiring overly complex integration processes.
Data Source
AI summary
An evaluation value is calculated based on a history of currents in order to quantitatively evaluate unevenness of an ion concentration in a non-aqueous electrolyte of a secondary battery. An integrated evaluation value for each of the discharging side and the charging side are calculated. When the integrated evaluation value exceeds a positive threshold value, discharging of the secondary battery is restricted, and when the integrated evaluation value exceeds a negative threshold value, charging of the secondary battery is restricted.