Battery Charge Termination Voltage Reduction via Dynamic Current Limiting
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Solution Overview
Problem
Existing battery charging systems face challenges in preventing battery voltage from exceeding a threshold, especially during sudden changes in system load, which can lead to potential damage and increased heat dissipation.
Innovation Solution
A charge control circuit that monitors battery voltage and adjusts the travel adapter's output current using load current information to prevent voltage thresholds from being exceeded, enabling a bypass charge path to reduce power dissipation and protect the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant-voltage charger applies a constant charging voltage at or near the desired full-charge voltage of the battery, then the battery charging voltage is maintained at the desired level, but the battery voltage may exceed the threshold during sudden load changes causing potential damage
Solution Approach 1:
The charge control circuit continuously monitors battery voltage and compares it against a threshold value. When the voltage approaches or exceeds the threshold during sudden load changes, the circuit automatically reduces the travel adapter's output current limit, preventing voltage exceedance and potential battery damage.
Solution Approach 2:
The system dynamically adjusts the travel adapter's output current limit based on real-time battery voltage conditions. The current limit is not fixed but varies according to the battery's instantaneous voltage state, allowing the system to respond to sudden load changes and prevent voltage threshold exceedance while maintaining efficient charging.
2Reliability
If a linear charger uses a pass transistor in an active mode to reduce travel adapter voltage to desired battery voltage, then the voltage is reduced to the desired level, but a relatively large amount of power is dissipated
Solution Approach 1:
The invention extracts the voltage regulation function from the linear charger's pass transistor and relocates it to the travel adapter's output stage. The travel adapter now directly provides voltage-regulated current to the battery, eliminating the need for the linear charger to dissipate power through the pass transistor while maintaining proper voltage regulation.
Solution Approach 2:
The charge control circuit acts as an intermediary between the travel adapter and the battery, managing the power transfer efficiently. By controlling the travel adapter's output current limit based on battery voltage feedback, the system avoids the power dissipation issues of linear regulation while ensuring safe and efficient charging.
3Productivity
If the travel adapter provides high output current to charge the battery quickly, then charging speed is improved, but the battery voltage may exceed the threshold during load changes
Solution Approach 1:
The travel adapter's output current limit is dynamically adjusted based on real-time battery voltage monitoring. During normal charging, high current is permitted for fast charging. When sudden load changes cause voltage to approach the threshold, the current limit is automatically reduced, preventing voltage exceedance while maximizing charging speed during safe operating conditions.
Solution Approach 2:
The charge control circuit continuously monitors battery voltage and provides feedback to the travel adapter's current limit control. This feedback mechanism allows the system to maintain high charging currents when safe, while automatically reducing current when voltage approaches the threshold, thus achieving both fast charging and voltage compliance.
Data Source
AI summary
This document discusses, among other things, apparatus, systems, and methods to prevent a voltage of a charging battery from exceeding a voltage threshold, including receiving charging information from a battery and controlling an output current of a travel adapter, including adjusting the received battery current information using a load current to prevent the voltage of the battery from exceeding a voltage threshold, and providing output current limit information to the travel adapter using the adjusted battery current information.