Dynamic Current Adjustment for Rechargeable Battery Charging
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Solution Overview
Problem
Existing rechargeable battery charging methods, such as constant current-constant voltage charging, often result in increased charging time due to reduced initial set current to prevent battery voltage from exceeding maximum allowable limits, especially in multi-cell batteries with cell-to-cell voltage variations.
Innovation Solution
A method that dynamically adjusts the set current based on real-time battery voltage and temperature conditions, increasing the current when the voltage remains below a designated threshold and reducing it when approaching full charge, while monitoring for over-charging conditions to maintain efficient charging within safe voltage limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the set current at the start of charging is reduced to prevent battery voltage from exceeding maximum allowable limits, then battery safety is improved, but charging time increases
Solution Approach 1:
The patent applies dynamics by transitioning from a static, conservative initial current setting to a dynamic current adjustment strategy. The charging control apparatus continuously monitors battery voltage and automatically adjusts the set current in real-time: starting with a higher current that would normally be unsafe, then increasing it further when voltage remains below a designated threshold, and reducing it only when approaching full charge. This dynamic adaptation resolves the contradiction by enabling faster charging while maintaining safety through continuous feedback control.
Solution Approach 2:
The patent implements feedback by establishing a closed-loop control system that continuously detects battery voltage and uses this information to adjust the charging current. The control apparatus compares the detected voltage against a designated threshold (lower than the maximum protection voltage) and automatically modifies the set current accordingly. This feedback mechanism allows the system to safely operate at higher currents than traditional methods while preventing overcharging, thus reducing charging time without compromising battery safety.
2Productivity
If the set current is increased to reduce charging time, then charging speed is improved, but battery voltage may exceed maximum allowable limits
Solution Approach 1:
The patent applies continuity of useful action by maintaining the charging process at optimally high current levels throughout the entire charging cycle, rather than using conservative current limits. The control apparatus continuously adjusts the current to be as high as safely possible, only reducing it when the voltage approaches full charge. This continuous optimization of current magnitude maximizes charging speed while the ongoing voltage monitoring ensures safety limits are never exceeded.
Solution Approach 2:
The patent implements parameter changes by dynamically modifying the set current parameter based on real-time battery voltage conditions. Instead of using a fixed conservative current value, the system changes the current parameter in response to voltage measurements, increasing it when voltage is well below the maximum limit and reducing it only when necessary. This parameter adaptation enables higher average charging current while maintaining voltage control safety.
3Reliability
If the set current is reduced below maximum current flow to account for battery degradation and cell variation, then battery protection is improved, but charging capacity utilization decreases
Solution Approach 1:
The patent applies preliminary action by establishing a designated voltage threshold lower than the maximum protection voltage before charging begins. This pre-set threshold provides a safety margin that allows the system to use higher initial currents without risking overcharging, even in batteries with degradation or cell variation. The control apparatus then uses this headroom to maintain higher currents for longer periods, improving charging capacity utilization while still protecting the battery through the buffer provided by the designated threshold.
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 allows for faster battery charging while ensuring the battery voltage does not exceed the maximum allowable limits, reducing charging time without compromising safety and capacity.
Implementation Method 1
detects battery voltage as a time-series and charges the rechargeable battery with a given amount of set current
Implementation Method 2
a rechargeable battery has non-negligible internal resistance. During charging, the voltage component generated by the set current flow through the internal resistance is added to the open-circuit voltage
Data Source
AI summary
When maximum cell voltage remains at or below a maximum current control voltage (4200 mV), which is below the start-full-charge detection voltage (4210 mV), three consecutive times with 250 ms periodicity, set current is increased one level (128 mA). When maximum cell voltage is higher than the start-full-charge detection voltage three consecutive times with 250 ms periodicity, set current is reduced. When maximum cell voltage is higher than the start-full-charge detection voltage and charging current remains below 384 mA two consecutive times with 250 ms periodicity, the rechargeable battery is determined to be fully-charged.