Traction Battery Charging with SOC-Triggered Discharge Intervals
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Solution Overview
Problem
Traction batteries in electric vehicles face issues with lithium precipitation during charging, which reduces performance and shortens cycle life, and poses safety risks such as combustion and explosion.
Innovation Solution
A method for charging traction batteries that involves obtaining state parameters like SOC, SOH, and temperature, and controlling discharging based on these parameters to prevent lithium precipitation, using a battery management system (BMS) to determine appropriate SOC intervals and discharging parameters, ensuring safety and improving charging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current is increased to improve charging speed, then the charge rate increases, but lithium precipitation occurs which reduces battery performance and safety
Solution Approach 1:
The patent implements periodic discharging actions during the charging process. The BMS controls the battery to perform discharging at specific intervals (when SOC reaches predetermined thresholds like 90%, 95%, 100%) to prevent lithium precipitation. This periodic discharging interrupts the continuous charging process, allowing lithium ions to redistribute and preventing dangerous accumulation that would occur with continuous high-current charging.
Solution Approach 2:
The patent applies preliminary action by proactively stopping charging before lithium precipitation becomes dangerous. The BMS monitors SOC in real-time and initiates discharging at predetermined thresholds (90%, 95%, 100%) before the battery reaches a fully charged state. This preventive approach eliminates lithium precipitation risks before they can develop, rather than reacting after the problem occurs.
2Duration of action of moving object
If the charging time is extended to ensure complete charging, then the SOC reaches 100%, but lithium precipitation occurs reducing battery life
Solution Approach 1:
The patent stops charging at predetermined SOC thresholds (90%, 95%, 100%) before complete charging would cause lithium precipitation. By proactively interrupting charging at these thresholds and implementing discharging actions, the system prevents battery damage and extends cycle life, rather than allowing extended charging that would degrade the battery.
Solution Approach 2:
The BMS continuously monitors the battery's SOC and implements feedback control by adjusting charging/discharging operations based on real-time battery state. When SOC reaches predetermined thresholds, the BMS triggers discharging actions and adjusts charging parameters accordingly. This closed-loop feedback system dynamically optimizes charging time while preventing lithium precipitation and extending battery life.
Data Source
AI summary
Provided are a method for charging a traction battery and a battery management system, which can improve the performance of a traction battery. The method for charging the traction battery is applied to a battery management system BMS of the traction battery, where the method includes: in a charging process of the traction battery, obtaining a state parameter of the traction battery, where the state parameter includes at least one of the following parameters: a state of charge SOC, a state of health SOH, and a temperature; determining an SOC interval value and a discharging parameter corresponding to discharging of the traction battery based on the state parameter of the traction battery, where the discharging parameter includes at least one of the following parameters: a discharging time, a discharging current, and a discharging waveform.