Battery Charging Circuit With Adaptive Full-Charge Voltage Detection
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Solution Overview
Problem
Existing battery charging methods, especially when using low-rated power AC adapters, often result in reduced battery capacity due to fixed taper voltage settings, which do not account for individual circuit resistance variations, leading to inaccurate full charge determination and decreased charging power.
Innovation Solution
A power supply circuit that dynamically updates the detection voltage based on specific charging conditions, estimating a second detection voltage when the battery reaches a fully charged state, allowing for more accurate full charge determination and adapting to individual electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed taper voltage is set lower by a margin than the rated system voltage to ensure safety and stability, then the charging system can operate reliably, but the battery may be incorrectly determined as fully charged before actually reaching full capacity, resulting in reduced battery capacity
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed taper voltage to a dynamic detection voltage that adapts based on circuit conditions. The detection voltage is no longer a static value set during design but is dynamically adjusted during charging operations to reflect actual circuit resistance values, allowing the system to maintain reliability while accurately detecting full charge states.
Solution Approach 2:
The patent implements parameter changes by modifying the detection voltage parameter from a fixed design-time value to a variable that changes based on runtime measurements. The system measures actual circuit resistance during charging and uses this information to adjust the detection voltage threshold, thereby changing the parameter to match actual operating conditions rather than relying on predetermined conservative estimates.
2Reliability
If individual differences in circuit resistance values are accounted for by setting larger safety margins, then charging system stability is improved, but charging power decreases and battery charging efficiency is reduced
Solution Approach 1:
The patent implements feedback by measuring the actual circuit resistance during charging operations and using this measured value to adjust the detection voltage. This closed-loop approach allows the system to receive feedback about actual operating conditions and modify its behavior accordingly, eliminating the need for conservative design margins while maintaining stability through real-time adaptation.
Solution Approach 2:
The system performs self-service by automatically measuring its own circuit resistance characteristics during normal operation and using this self-diagnosed information to optimize charging parameters. The charging circuit essentially characterizes itself during operation, eliminating the need for external calibration or conservative design assumptions about individual component variations.
3Device complexity
If a fixed detection voltage is used for full charge determination, then the control logic is simple and easy to implement, but inaccurate full charge detection occurs when system power consumption affects charging current
Solution Approach 1:
The patent introduces an intermediary measurement step by measuring circuit resistance as an intermediate parameter. Rather than directly using charging current and voltage alone for full charge detection, the system first measures the intermediary resistance value and uses this to calculate a corrected detection voltage threshold, improving accuracy without significantly complicating the control logic.
Data Source
AI summary
A circuit includes a power supply circuit which supplies, to a system, system power required for the system out of DC power supplied from a power supply, and charges a battery with charging power as remaining power. When a cell voltage of the battery is a predetermined detection voltage or more and a charging current of the charging power becomes a predetermined detection current or less, the power supply circuit determines that a charged state of the battery is fully charged. The cell voltage at a time when it is determined that the charged state is fully charged based on the cell voltage obtained in a specific charging state to the battery is estimated as a second detection voltage. The predetermined detection voltage is updated from a predetermined first detection voltage to the second detection voltage.