Charging Management Circuit with Elevated Cut-off Voltage
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Solution Overview
Problem
Conventional charging methods for lithium batteries are slow due to the lengthy constant voltage charging stage, which can lead to overcharging and damage when power consumption is high, as the charging current is reduced, affecting the true voltage of the cell.
Innovation Solution
A charging management circuit that performs constant current charging with a cut-off voltage greater than the rated voltage of the cell, ensuring the true voltage is not overvoltage, and includes a control circuit to stop charging when the cut-off voltage is reached, thereby prolonging the constant current charging time and preventing overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant voltage charging stage is used to charge the cell, then the cell voltage is maintained at a safe level, but the charging speed becomes slow
Solution Approach 1:
The patent changes the cut-off voltage parameter from the conventional rated voltage to a higher value (over-voltage) during constant current charging. This allows the charging process to maintain higher current for longer duration, significantly improving charging speed while the control circuit ensures the true voltage never exceeds safe limits, thus resolving the contradiction between safety and speed
2Productivity
If constant current charging is extended to improve charging speed, then the charging current remains high, but the cell may become overvoltage and damaged
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the voltage across the cell terminals and compares it with the rated voltage. Based on this feedback, the control circuit dynamically adjusts the charging current to ensure that even when using an elevated cut-off voltage for fast charging, the true voltage of the cell never exceeds safe operational limits, thus preventing overvoltage damage while maintaining high charging speed
3Reliability
If the constant current charging cut-off voltage is set to the rated voltage, then the cell is protected from overvoltage, but the charging time is prolonged
Solution Approach 1:
The patent applies a dynamic approach by setting the cut-off voltage higher than the rated voltage during constant current charging phase. The control circuit dynamically manages the charging process, allowing the terminal voltage to exceed the rated voltage temporarily while ensuring the true voltage remains protected. This dynamic voltage management enables faster charging by extending the constant current phase without compromising cell safety
Data Source
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AI summary
A charging management circuit, a terminal and a charging method are provided. The charging management circuit includes: a first output end, configured to perform constant current charging on a cell; a second output end, configured to supply power to a load in a constant current charging process; and a control circuit, configured to stop the constant current charging when a voltage across both ends of the cell reaches a constant current charging cut-off voltage of the constant current charging, wherein the constant current charging cut-off voltage is greater than a rated voltage of the cell, and is configured such that a true voltage of the cell is not overvoltage in the constant current charging. Performing the constant current charging with the charging management circuit and setting the constant current charging cut-off voltage to be greater than the rated voltage of the cell may raise a charging speed of the cell.