Li-Ion Charge Control for Load Drop and Lithium Plating Prevention
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Solution Overview
Problem
Existing charge controllers for lithium ion batteries fail to prevent lithium deposition when load-side consumption current reduces during charging, leading to potential overcharging and lithium deposition due to insufficient feedback control.
Innovation Solution
A charge control device that estimates inflow current upon load stoppage, derives a protective charging current and charging upper limit, and controls charging based on these values to prevent lithium deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to limit charging current, then lithium deposition is prevented under normal conditions, but the control cannot respond in time when load-side consumption current reduces significantly during charging
Solution Approach 1:
The control device performs preliminary estimation of the inflow current that would flow into the battery if the load current stops. Based on this estimation, it proactively adjusts the charging current limit before the actual current exceeds safe levels, preventing lithium deposition by acting in advance rather than reacting after the problem occurs.
2Productivity
If the charging current is increased to charge the battery faster, then charging efficiency is improved, but the risk of lithium deposition increases when load consumption reduces
Solution Approach 1:
The charging current limit is made dynamic rather than fixed. The control device continuously monitors load current and adjusts the charging current limit in real-time based on the estimated inflow current. This allows the system to maximize charging efficiency when load consumption is high while automatically reducing the charging current limit when load consumption drops, thereby preventing lithium deposition under varying operating conditions.
Data Source
AI summary
A charge control device is configured to control charging of a lithium ion battery, estimate an inflow current flowing into the lithium ion battery when a current flowing through a load stops, derive a protective charging current that is a maximum value of charging current not to cause the lithium ion battery to form lithium deposition, calculate a charging upper limit current based on the protective charging current and the inflow current, the charging upper limit current being an upper limit of current to charge the lithium ion battery, and control charging of the lithium ion battery based on a limit electric power calculated from the charging upper limit current and a voltage of the lithium ion battery.