Battery Charging System Dynamic State of Charge Management
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Solution Overview
Problem
Lithium-ion batteries in electric vehicles experience accelerated degradation when maintained at full charge levels, leading to reduced battery life during periods of inactivity, and existing charging strategies do not effectively balance the need for full charge readiness with battery longevity.
Innovation Solution
A battery charging system that maintains the state of charge at a partial level during storage periods and adjusts to an operating charge level just before use, utilizing historical drive cycle data to optimize charging and discharging, and allowing remote communication for dynamic adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery is maintained at full charge level during storage, then the battery is ready for immediate use, but the battery degradation accelerates and battery life reduces
Solution Approach 1:
The charging system dynamically adjusts the battery state of charge based on real-time conditions including storage duration, temperature, and usage patterns. The controller modifies charging parameters continuously rather than maintaining a fixed charge level, optimizing both battery longevity and readiness. This is achieved through continuous monitoring of battery voltage, current, and temperature sensors that feed back to the control algorithm.
Solution Approach 2:
The system changes key operating parameters such as charge voltage, charge current, and target state of charge based on storage time and environmental conditions. During long-term storage, the system maintains lower charge levels (e.g., 40-60% SOC) to reduce degradation, while during short-term storage or near usage, it charges to higher levels (80-100% SOC) to ensure readiness. Temperature compensation further adjusts these parameters dynamically.
2Productivity
If the battery is charged to operating charge level during storage, then vehicle range is maintained, but the amount of degradation to the battery increases
Solution Approach 1:
The system performs preliminary charging actions in advance of actual vehicle usage based on predicted storage duration and usage patterns. By analyzing historical data and user behavior, the controller pre-charges the battery to appropriate levels before the vehicle is needed, ensuring full range availability without maintaining high charge levels throughout the entire storage period, thereby minimizing degradation exposure.
Solution Approach 2:
The charging system implements periodic charge-discharge cycles or top-up charging at intervals during storage to maintain optimal battery health. Rather than continuously maintaining maximum charge, the system periodically replenishes charge to necessary levels, allowing the battery to rest at lower, less stressful charge states between charging events, reducing cumulative degradation while ensuring readiness.
3Reliability
If the charger continuously charges the battery to full capacity, then the battery is always ready for use, but the charging time and energy waste increase
Solution Approach 1:
The charging system incorporates multiple feedback mechanisms including state of charge estimation from voltage and current measurements, temperature feedback from thermal sensors, and usage pattern feedback from historical data. This multi-layer feedback enables the controller to accurately determine when sufficient charge has been achieved and to adjust charging termination points dynamically, preventing unnecessary charging time and energy waste while maintaining battery availability.
4Duration of action of stationary object
If the battery is maintained at partial charge level during storage, then battery degradation is reduced, but the vehicle range and drivability are affected
Solution Approach 1:
The system dynamically determines the optimal charge level during storage based on multiple factors including remaining storage duration, predicted temperature conditions, and anticipated usage requirements. The controller continuously adjusts the target state of charge, transitioning from lower levels during extended storage to higher levels as usage approaches, thereby optimizing the balance between degradation reduction and range maintenance without manual intervention.
Data Source
AI summary
A battery charging system includes a charger that is configured to charge and discharge a battery. The battery system further includes a controller programmed to operate the charger based on a state of charge of the battery to, during a storage duration, maintain the state of charge at a partial charge level. The charger may be operated to charge and discharge the battery during the storage duration. Upon expiration of the storage duration, the controller operates the charger to maintain the state of charge at an operating charge level. The partial charge level is selected to reduce an amount of degradation to the battery relative to the operating charge level for a same duration of time. The battery charging system includes remote connectivity such that the storage duration may be modified during the storage duration from a remote device.