Battery Management Threshold Control for Cell Voltage Imbalance
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Solution Overview
Problem
Battery cells in a pack exhibit varying available voltage ranges for charging and discharging due to differences in chemical properties, leading to capacity degradation and inconsistent performance despite cell balancing, particularly in lithium iron phosphate batteries.
Innovation Solution
A battery management apparatus with a processor that adjusts charging and discharging threshold voltages based on cell voltage differences and state of charge (SOC) to maximize capacity by setting adaptive threshold voltages using equations that consider maximum and minimum cell voltages and current SOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If cell balancing is performed to match voltage ranges of battery cells, then voltage consistency is improved, but capacity degradation still occurs due to repeated charging and discharging
Solution Approach 1:
The patent implements dynamic adjustment of charging and discharging threshold voltages based on real-time cell voltage differences and SOC states. Instead of using fixed threshold values, the system continuously adapts the thresholds to match the actual voltage ranges of individual cells, thereby optimizing charging/discharging windows and reducing capacity degradation while maintaining voltage consistency.
Solution Approach 2:
The patent changes the parameters of threshold voltages dynamically based on cell voltage deviations and SOC. By calculating maximum voltage deviations among cells and adjusting thresholds accordingly, the system optimizes the charging and discharging voltage ranges for each cell, preventing capacity degradation while maintaining voltage consistency across the battery pack.
2Device complexity
If fixed charging and discharging threshold voltages are used, then control simplicity is maintained, but capacity utilization is reduced due to voltage variations among cells
Solution Approach 1:
The system transitions from static fixed thresholds to dynamic adaptive thresholds that automatically adjust based on cell voltage differences and SOC. This dynamic approach maximizes capacity utilization by optimizing charging/discharging windows for each cell while maintaining manageable control complexity through automated calculations and processor-based implementation.
Solution Approach 2:
The battery management system performs self-adjustment by automatically calculating voltage deviations, determining optimal threshold values, and adapting charging/discharging parameters without external intervention. This self-service capability maximizes capacity utilization while keeping the control system relatively simple, as the processor autonomously handles the complex adjustments.
3Productivity
If charging threshold voltage is increased to maximize capacity, then capacity utilization is improved, but risk of overcharging increases for cells with higher voltage
Solution Approach 1:
The patent applies different charging threshold adjustments to different cells based on their individual voltage characteristics. Cells with lower voltage ranges receive higher threshold adjustments to maximize their capacity utilization, while cells with higher voltage ranges maintain lower thresholds to prevent overcharging. This localized quality approach ensures each cell operates within its optimal and safe voltage window.
Solution Approach 2:
The system dynamically changes threshold parameters for each cell based on real-time voltage measurements and SOC states. By calculating maximum voltage deviations and adjusting thresholds individually, the system optimizes capacity utilization for each cell while inherently preventing overcharging, as the thresholds are specifically tailored to each cell's voltage characteristics and current state.
Data Source
AI summary
A battery management apparatus includes a measuring unit including at least one sensor, the measuring unit configured to measure a cell voltage of each of a plurality of battery cells in a battery module, and a processor configured to adjust a charging threshold voltage or a discharging threshold voltage based on a difference in cell voltage between the plurality of battery cells and a current state of charge (SOC) of the battery module if charging or discharging the battery module.