Battery Charging Circuit Mode Switching Stabilization
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Solution Overview
Problem
Existing battery charging circuits face challenges in stabilizing charging current during mode switching from trickle charge to fast charge, leading to overshooting and excessive current delivery, which can stress lithium ion batteries.
Innovation Solution
A battery charging circuit with a comparison circuit that lowers the current restriction reference voltage before switching modes and returns it to the original value, using a slope limit circuit to adjust voltage variation and prevent overshooting, ensuring the charging current remains within normal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current is increased to fast charge mode, then the charging speed is improved, but the charging current overshoots and becomes excessive during mode switching
Solution Approach 1:
The patent applies preliminary action by lowering the current restriction reference voltage before the mode switching from trickle charge to fast charge occurs. This preemptive adjustment prevents charging current overshooting by ensuring the reference voltage is already at the appropriate lower level when the switching signal is generated, thereby maintaining current stability while enabling fast charging.
Solution Approach 2:
The patent applies preliminary anti-action by counteracting the potential harmful effect of current overshoot before it occurs. By lowering the current restriction reference voltage in advance, the system creates a compensatory effect that offsets the inevitable voltage drop and current surge during mode switching, thus preventing excessive current delivery to the battery.
2Reliability
If the current restriction reference voltage is lowered before mode switching, then the charging current stability is improved, but the voltage variation increases during switching
Solution Approach 1:
The patent applies feedback by using a slope limit circuit that monitors and controls the variation of the current restriction reference voltage. The slope limit circuit ensures that the voltage is lowered gradually at a controlled rate rather than abruptly, thereby reducing voltage variation and shock during mode switching while still preventing charging current overshooting.
Solution Approach 2:
The patent applies dynamics by making the current restriction reference voltage adjustable and time-dependent. The voltage is dynamically modified based on the switching phase: lowered before switching to prevent overshoot, and then restored after switching completes. This dynamic adjustment optimizes both current stability and voltage variation control throughout the switching process.
Data Source
AI summary
A battery charging circuit that stabilizes operation when switching between charge modes includes first and second transistors. The first transistor has a source connected to a first switch circuit. The first switch circuit connects the second transistor to either one of first and second external terminals. A mode switch circuit generates a switch signal for switching from a trickle charge mode to a fast charge mode. The mode switching circuit provides the switching signal to a comparison circuit. After a predetermined time elapses, the mode switching circuit provides the switching signal to the switch circuit. The comparison circuit lowers a current restriction reference voltage, which determines a charging current value, and returns the current restriction reference voltage to its original value after switching modes.