Charge Protection Circuit Timing Function Lithium-Ion Battery
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Solution Overview
Problem
Conventional battery protection circuits for lithium-ion batteries face challenges in accurately determining overcharge, leading to potential damage from overcharging, overdischarging, and overcurrent, necessitating a solution to prevent overcharging by terminating the charging process based on predetermined charge time.
Innovation Solution
A charge protection circuit with a timing function is introduced, incorporating a control IC with an overcharge control terminal, a charge delay trigger terminal, a second capacitor, and a timing circuit featuring operational amplifiers and capacitors, which generates signals to switch off the second switch when a predetermined voltage is reached, preventing overcharging of lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional battery protection circuits are used, then the circuit structure is simple, but the overcharge detection accuracy is insufficient
Solution Approach 1:
The protection circuit is segmented into functional modules: overcharge detection module (comparing actual voltage with reference voltage), timing module (controlling charge time duration), and control module (switching charging off). This segmentation allows each module to perform its function independently, improving overall detection accuracy while keeping individual modules relatively simple.
Solution Approach 2:
The circuit performs preliminary actions by pre-setting reference voltages, charge time thresholds, and switching parameters before charging begins. The timing module pre-calculates the required charge time, and the detection module pre-establishes voltage thresholds, enabling accurate overcharge detection without complex real-time calculations.
2Productivity
If charge time is extended to ensure full charging, then charging completeness is improved, but overcharge risk increases
Solution Approach 1:
The circuit implements feedback mechanisms where the detection module continuously monitors charging voltage and current, comparing them against pre-set thresholds. When the battery voltage reaches the reference voltage or charge time reaches the threshold, the feedback signal triggers the control module to switch off charging, ensuring both complete charging and overcharge prevention.
Solution Approach 2:
The circuit dynamically changes operating parameters during charging: it monitors voltage changes over time, adjusts the charge current based on battery state, and modifies the switching timing parameters. This parameter adaptation allows the circuit to achieve full charging while automatically preventing overcharge conditions.
3Device complexity
If voltage threshold detection is used, then overcharge detection is simplified, but detection accuracy under varying conditions deteriorates
Solution Approach 1:
The detection module uses voltage comparison against a stable reference voltage to determine charging status. By maintaining equipotential reference levels and comparing the actual battery voltage against this stable reference, the circuit achieves accurate detection regardless of external voltage variations or battery state changes.
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
The circuit effectively terminates the charging process based on predetermined charge time, preventing lithium-ion batteries from being overcharged, thereby enhancing protection against overcharging, overdischarging, and overcurrent issues.
Implementation Method 1
the output terminal of the first operational amplifier outputs a first high level signal for charging the first capacitor to raise the voltage of the noninverting input terminal of the second operational amplifier
Implementation Method 2
the second operational amplifier outputs a second high level signal to charge the second capacitor, a voltage applied to the Ct terminal of the control IC rises during the charging of the capacitor
Data Source
AI summary
A charge protection circuit with a timing function is disclosed. The circuit includes a charge protection module constituting of a second switch, a second capacitor and a control integrated circuit (IC). The second switch Q2 is switched to turn on or turn off to charge or discharge the lithium-ion battery. The second capacitor configured for setting a delay time of a Ct terminal of the control IC, thus to prevent the battery from being overcharged. The circuit further includes a charge timing circuit configured for predetermining a time threshold value. When the charge time reaches the time threshold value, the charge timing circuit outputs a second high level signal to charge the second capacitor. The second capacitor triggers the control IC to turn off the second switch, thereby terminating the charge of the battery body.