Parked EV Battery Charge-State Control to Limit Aging
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Solution Overview
Problem
Lithium-ion batteries in electric vehicles experience accelerated aging due to high charge states and temperatures, leading to capacity loss, with existing methods either requiring route data for optimized charging or only analyzing wear without prevention.
Innovation Solution
A method involving a control apparatus that determines the vehicle's operating state, lowers the battery charge state when above a defined limit, and maintains it below a second limit to minimize aging, using air conditioning or energy feedback to achieve partial discharging and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery charge state is maintained at high levels to ensure sufficient power for future use, then the available power for driving is improved, but the battery aging rate increases exponentially
Solution Approach 1:
The control apparatus performs preliminary action by determining the parking duration before the vehicle is parked and proactively adjusting the charge state limit value accordingly. When long parking is predicted, the system lowers the charge state limit before parking occurs, preventing aging acceleration. When short parking is predicted, the system maintains higher charge states to ensure sufficient power availability after parking.
Solution Approach 2:
The charge state limit value is made dynamic rather than fixed. The control apparatus continuously adjusts the charge state limit value based on real-time parking duration predictions. This dynamic adjustment allows the system to optimize between power availability and aging prevention for each specific parking scenario, rather than using a static charge limit.
2Reliability
If the charge state is actively lowered to reduce battery aging, then the battery lifespan is extended, but the available power for subsequent use is reduced
Solution Approach 1:
The charge state limit value dynamically adapts based on predicted parking duration. For short parking scenarios, the limit remains high to preserve power availability. For long parking scenarios, the limit is lowered to extend battery lifespan. This dynamic approach ensures optimal balance between lifespan extension and power availability for each specific case.
Solution Approach 2:
The system changes the charge state parameter based on parking duration predictions. By adjusting the charge state limit value as a function of predicted parking duration, the system optimizes the balance between reducing aging and maintaining sufficient power. The charge state parameter is modified only when necessary, based on predicted parking scenarios.
3Device complexity
If a fixed charge state limit is used to simplify control, then the system complexity is reduced, but the optimization effectiveness for different parking durations is lost
Solution Approach 1:
The control apparatus performs preliminary determination of parking duration before the vehicle is parked. This preliminary information is then used to set an appropriate charge state limit value. By determining the parking scenario in advance, the system can proactively optimize the charge state without requiring complex real-time adjustments during parking.
Solution Approach 2:
The system uses feedback from parking duration predictions to adjust the charge state limit value. The control apparatus receives information about predicted parking duration and uses this feedback to determine the optimal charge state limit. This feedback mechanism enables adaptive optimization while maintaining relatively simple control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces battery aging while ensuring sufficient power is retained for future use, avoiding excessive charge states that accelerate degradation, and doing so in a simple and cost-effective manner.
Implementation Method 1
The higher the charge state of the battery, the faster side reactions that accelerate aging take place in the battery. The speed of the side reactions is disproportionate to the charge state. This means that an additional increase in the charge state results in a progressive increase in the speed of the side reactions. Above a charge state of about 80%, the increase in the rate of the side reactions is already exponential relative to the increase in the charge state.
Implementation Method 2
The rate of these side reactions also increases with increasing temperatures. Therefore, leaving a motor vehicle with a fully charged battery parked for a long time in relatively high outside temperatures is particularly disadvantageous for the aging of the battery.
Data Source
AI summary
A method for operating a battery of a parked motor vehicle includes determining an operating state of the motor vehicle, determining a current charging state of the battery when the operating state of the motor vehicle is a parked state, determining a first upper charging state limit value of the battery, first active lowering of the charging state of the battery when the current charge state is greater than the first upper charging state limit value, determining a second upper charging state limit value of the battery, and ending the first active lowering of the charging state when the charge state of the battery falls below the second upper charging state limit value. The invention also relates to a motor vehicle.