Traction Battery Charging Thresholds for Heat and Lithium Plating
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Solution Overview
Problem
The safety performance of traction batteries in electric vehicles is compromised due to continuous charging, which can lead to lithium precipitation, heating, and potential safety hazards such as fires or explosions, necessitating a method to ensure safe charging practices.
Innovation Solution
A method and battery management system (BMS) that monitor temperature and battery parameters like state of charge (SOC) and open-circuit voltage (OCV) to control charging, discharging, or temporarily stopping the charging process when specific thresholds are met, thereby preventing lithium precipitation and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous charging is applied to traction battery, then charging efficiency is improved, but safety performance deteriorates due to heating and lithium ion accumulation
Solution Approach 1:
The patent implements periodic charging and discharging cycles instead of continuous charging. The control unit alternates between charging mode and discharging mode, allowing the battery to rest and dissipate heat during discharge periods, thereby preventing continuous heat accumulation and lithium ion deposition while maintaining overall charging efficiency.
Solution Approach 2:
The patent employs real-time monitoring of battery temperature and state of charge (SOC) with feedback control. The control unit adjusts charging parameters based on temperature feedback, reducing or pausing charging when temperature thresholds are exceeded, thus preventing thermal runaway and safety hazards while optimizing charging efficiency under normal conditions.
2Productivity
If charging rate is increased to reduce charging time, then productivity is improved, but temperature increase and safety risks worsen
Solution Approach 1:
The patent dynamically adjusts charging rate based on real-time battery temperature and SOC conditions. The control unit modifies charging current and voltage levels adaptively, allowing high charging rates when temperature is low and safety margins are adequate, while automatically reducing rates when temperature rises, thus optimizing charging speed without compromising thermal safety.
3Use of energy by moving object
If charging continues without interruption to maximize energy input, then energy efficiency is improved, but lithium precipitation and safety hazards increase
Solution Approach 1:
The patent implements preliminary discharge action before resuming charging when temperature thresholds are approached. By initiating a discharge phase before lithium precipitation becomes critical, the system prevents harmful lithium deposition while maintaining overall energy efficiency through optimized charging-discharge scheduling.
Data Source
AI summary
A method for charging a traction battery applied to a battery management system (BMS) for the traction battery, includes obtaining a temperature and a battery parameter of the traction battery, determining a parameter threshold based on the temperature of the traction battery, and during a charging process of the traction battery, controlling the traction battery to discharge or stop being charged in response to the battery parameter of the traction battery being greater than or equal to the parameter threshold and the battery parameter of the traction battery changing by a parameter gap value. The battery parameter includes at least one of a state of charge (SOC) or an open-circuit voltage (OCV).