Battery Charging Current Control Using Internal Resistance Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charging methods for secondary batteries, such as lithium-ion batteries, struggle to accurately suppress the degradation of battery performance due to factors like lithium precipitation during low-temperature charging.
Innovation Solution
A charging control apparatus and method that control the charging current and internal resistance of secondary batteries by setting a threshold for the product of charging current and internal resistance, considering factors like overvoltage, temperature, and capacity retention rate, to prevent excessive degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charging control is performed by adjusting allowable input power based on negative electrode potential, then lithium precipitation can be suppressed, but accurate measurement and control of negative electrode potential becomes complex and difficult to implement
Solution Approach 1:
The patent introduces an intermediary approach by using terminal voltage and charging current as measurable proxies instead of directly measuring negative electrode potential. The control unit calculates the product of terminal voltage and charging current to infer the electrochemical state, avoiding the need for complex negative electrode potential measurement while still achieving effective charging control and lithium precipitation suppression
Solution Approach 2:
The patent replaces the complex electrochemical measurement system (negative electrode potential measurement) with a simpler electrical measurement system (terminal voltage and current measurement). By substituting the measurement approach from direct electrochemical potential sensing to electrical parameter measurement and calculation, the system achieves the same control objective with reduced complexity
2Productivity
If high charging current is applied to increase charging speed, then productivity improves, but battery performance degradation accelerates due to increased internal resistance effects
Solution Approach 1:
The patent implements dynamic charging control by continuously monitoring the product of terminal voltage and charging current, and adjusting the charging current in real-time. The control unit dynamically modifies the charging profile based on the calculated value, allowing the system to operate at high currents when safe and reduce current when approaching degradation thresholds, thus optimizing both charging speed and battery health
Solution Approach 2:
The patent employs feedback control by continuously measuring terminal voltage and charging current, calculating their product, and using this information to adjust the charging current. The control unit modifies the charging parameters based on the feedback from the calculated value, creating a closed-loop system that prevents battery degradation while maintaining high charging productivity
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
This approach effectively suppresses battery degradation by maintaining the product of charging current and internal resistance below a predetermined threshold, thereby enhancing battery performance and extending its lifespan.
Implementation Method 1
a product of the charging current and the internal resistance is smaller than or equal to a predetermined threshold
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An object is to easily suppress the degradation of battery performance during charging. A charging control apparatus controls charging of a secondary battery 1 that is performed by supplying power from a power source 3, and includes: a control unit 18 configured to control power supplied from the power source 3; and a resistance acquisition unit 17 configured to obtain an internal resistance 5 of the secondary battery 1. The power source 3 can change a charging current 6 and supply power to the secondary battery 1. The control unit 18 performs suppression control on the power source 3 such that the product of the charging current 6 and the internal resistance 5 is smaller than or equal to a predetermined threshold 8.