Digital Controller for USB-Powered Battery Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Battery-driven portable devices face challenges in simultaneous operation and charging from power supplies with limited current capacity, such as USB ports, where the current demand for device operation and charging can exceed the supply limits, potentially leading to overcurrent situations and voltage drops.
Innovation Solution
A system comprising a supply regulator with current limiting circuitry, a capacitor for filtering, and a digital controller that adjusts the charging current based on voltage comparisons to ensure the system current has precedence over charging current, preventing voltage drops by dynamically managing the charge current within the power supply's limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the portable device draws maximum current from the power supply for operation, then the device operation performance is improved, but the battery charging current becomes insufficient or impossible
Solution Approach 1:
The patent implements dynamic current allocation where the supply regulator continuously adjusts the current distribution between device operation and battery charging based on real-time voltage monitoring. When voltage drops indicate high current demand, the system dynamically reduces charging current to maintain stable operation, and increases charging current when voltage is stable, creating a dynamic balance between the two competing power demands.
Solution Approach 2:
The system employs feedback control through voltage monitoring and comparison. The voltage comparator continuously compares the actual voltage with a reference voltage, and this feedback signal controls the supply regulator to adjust current allocation. This closed-loop feedback mechanism ensures that the system automatically responds to voltage changes and maintains optimal current distribution between operation and charging.
2Reliability
If the supply regulator limits output current to prevent overcurrent conditions, then system safety is improved, but the total power available for both operation and charging is reduced
Solution Approach 1:
The patent changes the control parameter from direct current limiting to voltage-based indirect control. Instead of directly limiting current to a fixed value, the system monitors voltage and uses this parameter to indirectly control current allocation. This allows the system to safely operate near the maximum current capacity of the power supply by dynamically adjusting current based on voltage conditions, thereby maximizing power utilization while maintaining safety.
3Productivity
If the system prioritizes battery charging current, then charging speed is improved, but the device operation voltage drops and operation becomes unstable
Solution Approach 1:
The voltage monitoring and comparison circuit provides continuous feedback on voltage stability. When voltage drops occur during charging, this feedback signal immediately triggers the supply regulator to reduce charging current, preventing further voltage degradation. This feedback mechanism ensures that charging speed is maximized only when voltage stability is maintained, automatically prioritizing voltage stability when conflicts arise.
Solution Approach 2:
The supply regulator acts as an intermediary between the power supply and the battery charger, mediating the current distribution. It receives the power supply output and intelligently allocates current between device operation and battery charging based on voltage conditions, preventing direct conflict between the two power demands and ensuring neither operates at the expense of the other's stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for safe and efficient simultaneous operation and charging of portable devices from limited current sources, prioritizing system current over charging current to maintain stable voltage and prevent overcurrent conditions, thereby ensuring reliable operation and charging.
Implementation Method 1
the output of the supply regulator is further connected to a power input of a battery charger, charging the rechargeable battery, to a first terminal of a capacitor
Data Source
Figure 1~2
AI summary
Circuits and methods to charge batteries of a portable device simultaneously with supplying power to the device for its operation, using a power source with limited maximum current, as e.g. an USB port, have been achieved. The system invented relies upon digital control only. No direct sensing of the current required for the operation of the portable device is required. The control takes care that the sum of the charging current and of the current to run the portable device does not exceed the maximum allowable current of the power source. The current required to run the portable device has precedence over the charging current.