Traction Battery SoC Band Control for Slower Aging
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Solution Overview
Problem
Conventional lithium-ion batteries in motor vehicles experience accelerated aging and mechanical expansion due to fluctuations in state of charge, leading to a reduced lifetime and inefficient energy throughput.
Innovation Solution
Adjusting the minimum and maximum state of charge limits of the traction battery based on predefined parameters to maintain an optimal state of charge band, thereby slowing down the aging process and extending the battery's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the state of charge band is kept large to maximize energy throughput, then energy throughput is improved, but aging of the battery accelerates
Solution Approach 1:
The patent applies dynamics by making the state of charge limits adjustable rather than fixed. The minimum state of charge and maximum state of charge are dynamically adapted based on the battery's age and current condition, allowing the system to optimize between energy throughput and battery lifetime at different stages of the battery's life cycle
Solution Approach 2:
The patent changes the parameters of minimum state of charge and maximum state of charge based on the battery's age and condition. By adjusting these parameters dynamically, the system resolves the contradiction between maximizing energy throughput and extending battery lifetime
2Reliability
If the minimum state of charge is increased and/or maximum state of charge is decreased to slow aging, then battery lifetime is improved, but energy throughput decreases
Solution Approach 1:
The system dynamically adjusts the state of charge band based on battery age and condition rather than applying a static restriction. This allows the battery to operate with larger state of charge bands when young (maximizing energy throughput) and with restricted bands when aged (extending lifetime)
Solution Approach 2:
The patent performs preliminary assessment of battery age and condition to determine appropriate state of charge limits. By evaluating battery health in advance and adjusting limits proactively, the system prevents excessive aging while maximizing energy throughput during the battery's productive life
3Reliability
If the state of charge band is restricted to an optimum band, then aging is reduced, but the usable capacity is reduced
Solution Approach 1:
The optimum state of charge band is not fixed but dynamically adjusted based on battery age and condition. The system transitions from larger usable capacity bands when the battery is young to more restricted optimum bands when the battery shows signs of aging
Solution Approach 2:
The system performs preliminary evaluation of battery health parameters to determine when and how to restrict the state of charge band. This proactive approach allows the battery to maintain maximum usable capacity during its prime while preventing accelerated aging
Data Source
AI summary
A method for operating a traction battery for a motor vehicle, which can be discharged down to a predefined minimum charging state during operation of the motor vehicle and can be charged up to a predefined maximum charging state in a charging operation, wherein, the minimum charging state is increased and/or the maximum charging state is decreased if a limit value is reached by the value of a predefined parameter which describes a variable property of the traction battery.