Adaptive Charger Input Current Limiting for USB Overload Protection
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Solution Overview
Problem
Switched-type chargers face limitations in output power and current due to restricted input current from universal serial bus (USB) interfaces, leading to potential overload conditions and inefficient battery charging.
Innovation Solution
An adaptive charger with an input current limitation system, featuring a power converter and current feedback loop that compares input current against a reference signal, regulates input current, and determines overload states based on input voltage, gradually reducing current to prevent overload and optimize external power supply usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the input current of the charger is limited to avoid overload conditions when using USB power supply, then the reliability of the external power supply is improved, but the charging speed and output power are reduced
Solution Approach 1:
The charger dynamically adjusts the current reference signal based on detected overload conditions. When an overload is detected, the current reference signal is reduced to limit input current; when no overload is present, the current reference signal is increased to enable faster charging. This dynamic adjustment resolves the contradiction between reliability and charging speed.
Solution Approach 2:
The system uses feedback from overload detection to control the current reference signal. The detector monitors whether the external power supply is in an overload state, and this feedback information is used to adjust the current reference signal accordingly, enabling the charger to adaptively balance reliability and charging performance.
2Duration of action of stationary object
If the input current is limited to prevent overload, then the lifespan of external power supplies is extended, but the output power and charging efficiency are reduced
Solution Approach 1:
The charger employs dynamic control of the current reference signal that adjusts in real-time based on the external power supply's load condition. When the supply is not overloaded, higher current reference signals enable maximum output power; when overloaded, the reference signal is reduced to protect the supply, thus extending its lifespan while maintaining optimal power output when possible.
Solution Approach 2:
The system changes the parameter of the current reference signal based on detected overload conditions. By adjusting this key parameter, the charger optimizes the balance between protecting the external power supply (extending lifespan) and maintaining high output power for efficient charging.
Data Source
AI summary
An adaptive charger can include: a power converter configured to receive an input current from an external power supply, and to generate an output current as a charging current to a load; a current feedback loop configured to compare a first detection signal that represents the input current against a first current reference signal, and to generate a first error signal, where the power converter is configured to regulate the input current according to the first error signal; and the current feedback loop being configured to determine an overload state of the external power supply according to an input voltage of the power converter, where the charger is configured to enter a current limit state when the external power supply is determined to be in the overload state, and where the first current reference signal is gradually reduced until the external power supply recovers to a non-overloaded state.