Charging Circuit Voltage Difference Timer Control
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Solution Overview
Problem
Existing charging circuits for serially charging multiple secondary batteries with different charge levels require complex configurations and high manufacturing costs, leading to potential battery degradation due to overcharging.
Innovation Solution
A charging circuit with a power source, a single switch, and a control device that detects voltage differences among batteries, sets a timer, and adjusts the charging time based on thresholds to ensure all batteries reach a minimum charge level before finishing serial charging, thereby preventing prolonged overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching between individual charging and serial charging is implemented to equalize battery charge levels, then battery degradation due to overcharge is inhibited, but circuit complexity and manufacturing cost increase due to requiring at least three switches
Solution Approach 1:
The patent extracts the battery equalization function from the charging control logic and implements it through a timer-based mechanism rather than through additional switching circuits. The control device detects voltage differences, starts a timer with a predetermined period, and controls the switch to open before the timer expires if the voltage difference exceeds a threshold, thereby eliminating the need for separate individual charging circuits while maintaining battery protection.
Solution Approach 2:
The system uses the existing switch and timer components to automatically manage both charging control and battery equalization functions. The control device self-adjusts the charging process by monitoring voltage differences and dynamically controlling the switch timing, making the system self-regulating without requiring external complex switching infrastructure.
2Reliability
If switching between individual charging and serial charging is implemented to equalize battery charge levels, then battery degradation due to overcharge is inhibited, but manufacturing cost increases due to requiring at least three switches
Solution Approach 1:
The patent makes the existing switch and control device multi-functional by enabling them to perform both charging control and battery equalization tasks. The control device uses the same switch to implement voltage-difference-based charging termination, thereby eliminating the need for additional switches and reducing manufacturing costs while maintaining battery protection capabilities.
Solution Approach 2:
The equalization function is extracted from dedicated hardware circuits and implemented through software/control logic using existing components. This approach removes the need for additional physical components (switches) that would increase manufacturing cost, while preserving the protective function against battery degradation.
3Productivity
If serial charging is performed on batteries with different charge levels until all are fully charged, then charging efficiency is improved, but battery degradation occurs due to prolonged overcharging of batteries with higher initial charge levels
Solution Approach 1:
The control device performs preliminary detection of voltage differences between batteries before initiating the charging process. Based on this preliminary information, it pre-calculates the appropriate timing to open the switch during charging, thereby preventing overcharging of batteries with higher initial charge levels while maintaining efficient serial charging operation.
Solution Approach 2:
The system continuously monitors battery voltages during charging and uses this feedback to dynamically control the switch timing. When the voltage difference between batteries exceeds a predetermined threshold, the control device adjusts the charging termination time accordingly, ensuring that batteries with higher initial charge levels are not overcharged while maintaining overall charging efficiency.
Data Source
Figure 1
Figure 2
AI summary
A charging circuit 1 includes a first power source circuit 11 that supplies charging power to secondary batteries B1, B2; a switch SW that controls the supply of the power; and a control device 13 that performs switching control of the switch SW. The control device 13 detects a voltage difference between the secondary batteries B1, B2 before starting charging; starts a timer and starts serial charging of the secondary batteries B1, B2; on the condition that the voltage difference before the charging has been equal to or larger than a first threshold, if respective voltage values of the secondary batteries B1, B2 have both become equal to or larger than a second threshold before the timer expires, shortens a remaining time on the timer at that time point; and finishes the serial charging of the secondary batteries B1, B2 at the earlier of a time point when the secondary batteries B1, B2 have both become fully charged, or a time point when the timer has expired.