Battery Cell Switching Control for Uneven SoC and SoH
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Solution Overview
Problem
Traditional battery management systems face limitations in flexibility and efficiency due to uneven charging and discharging characteristics among battery cells, leading to reduced capacity, efficiency, and potential thermal runaway issues, especially in lithium ferrophosphate batteries where the formation of a solid-electrolyte interphase layer increases internal resistance and reduces battery life.
Innovation Solution
A battery control system (BCS) that dynamically controls the charging and discharging current of each battery cell based on its state of charge (SoC) and state of health (SoH), using switching circuits and a controller to optimize cell performance, facilitate individualized control, and extend the life of cells by maintaining comparable SoC and minimizing SoH deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional fixed configuration battery architectures are used, then system simplicity is maintained, but battery management flexibility and efficiency deteriorate due to uneven charging/discharging characteristics among cells
Solution Approach 1:
The battery system is divided into multiple independently controllable cell groups, each with its own switching circuit. This segmentation allows individual cells to be managed separately based on their specific state of charge and health, enabling flexible battery management while maintaining system controllability through modular architecture.
Solution Approach 2:
The system dynamically reconfigures battery cell connections using switching circuits controlled by a microcontroller. The switching states are adjusted in real-time based on cell voltage, current, and temperature measurements, allowing the system to adapt to changing battery conditions and optimize charging/discharging patterns for each cell.
2Reliability
If all battery cells are charged and discharged uniformly, then system operation is simplified, but weaker cells deteriorate faster and limit the operational cycle of the entire battery collective
Solution Approach 1:
Each battery cell is equipped with individual monitoring and control through dedicated switching circuits. The system applies different charging/discharging strategies to different cells based on their specific state of charge and health conditions, allowing weaker cells to be protected while stronger cells can operate at higher rates, thus improving both reliability and overall productivity.
Solution Approach 2:
The system changes operational parameters (current, voltage, switching states) for each battery cell based on real-time measurements. By adjusting these parameters dynamically according to cell-specific conditions, the system optimizes both the longevity of weaker cells and the overall charging/discharging efficiency of the battery collective.
3Adaptability or versatility
If battery cells with different state of charge and state of health are used, then system adaptability improves, but control complexity increases
Solution Approach 1:
The switching circuits serve multiple functions: they enable individual cell isolation, control charging/discharging current distribution, and facilitate cell balancing. This multi-functionality allows the system to handle battery cells with different states of charge and health using a unified control approach, improving adaptability without proportionally increasing control complexity.
Solution Approach 2:
The system continuously monitors battery cell parameters (voltage, current, temperature) and uses this feedback to dynamically adjust switching states and control signals. This closed-loop control enables the system to adapt to cells with varying states of charge and health while maintaining manageable control complexity through automated decision-making based on real-time data.
Data Source
AI summary
A battery control system includes a plurality of battery cells that are separately controllable as units of individual cells or groups of cells. Each controllable unit may be switchably activated or deactivated in the overall battery circuit, and one or more conditions of each controllable unit may be individually measured. Various techniques are disclosed for operating the battery control system to optimize or improve system performance and longevity.