PWM Charging Current Control via RC Filter Voltage
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Solution Overview
Problem
Conventional battery charging systems require multiple resistors and switching transistors to adjust charging currents, leading to increased cost and circuit area, and lack efficient temperature monitoring for battery protection.
Innovation Solution
A PWM signal with adjustable duty cycle is used to control the charging current, combined with an RC filter circuit to generate the necessary voltage for the charging IC, and temperature monitoring to adjust the duty cycle and protect the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple resistors and switching transistors are used to adjust charging currents, then different charging current requirements are met, but circuit area and cost increase
Solution Approach 1:
The patent changes the control parameter from discrete resistor selections to continuous PWM duty cycle adjustment. The charging current is controlled by varying the duty cycle of a PWM signal, which modulates the average current through the charging IC. This allows continuous adjustment of charging current without requiring multiple discrete resistors and switching transistors, thereby reducing circuit area while maintaining adaptability.
Solution Approach 2:
The patent replaces the mechanical/discrete component selection system (multiple resistors and switching transistors) with an electronic control system using PWM signals. Instead of physically switching between different resistor configurations, the system uses a microcontroller to generate PWM signals that electronically adjust the charging current, eliminating the need for complex discrete component networks.
2Adaptability or versatility
If multiple resistors and switching transistors are used to adjust charging currents, then different charging current requirements are met, but device complexity increases
Solution Approach 1:
The patent makes the PWM signal generation and duty cycle control serve multiple functions: it controls the charging current magnitude, enables temperature-based current reduction, and provides a unified control interface. This multi-functional approach eliminates the need for separate control circuits for each charging current level, simplifying the overall device complexity while maintaining versatility.
Solution Approach 2:
The patent extracts the current adjustment function from the discrete component network (resistors and switching transistors) and consolidates it into a single PWM control mechanism. By taking out the complex component selection logic and replacing it with a unified PWM duty cycle control, the circuit complexity is significantly reduced while preserving the ability to provide different charging currents.
3Reliability
If temperature monitoring is added to protect battery from overheating, then battery protection is improved, but device complexity increases
Solution Approach 1:
The patent merges the temperature monitoring function with the existing PWM control system. The microcontroller that generates PWM signals also reads temperature sensor data and adjusts the duty cycle accordingly. This integration means no separate control circuit is needed for temperature protection, as the same PWM controller handles both current regulation and thermal management, thus improving reliability without significantly increasing complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature sensor continuously monitors battery temperature and feeds this information back to the PWM controller. Based on the temperature reading, the controller automatically adjusts the PWM duty cycle to reduce charging current when overheating is detected. This closed-loop feedback system provides effective battery protection while using the existing control infrastructure, minimizing additional complexity.
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 approach allows for flexible adjustment of charging currents without the need for extensive circuitry, reducing costs and area, while also monitoring and protecting the battery from overheating.
Implementation Method 1
a RC filter circuit is used for performing an integration of the PWM signal to produce the corresponding voltage
Data Source
AI summary
A charging method and a charging system are introduced for controlling a charging current by a PWM method. A charging IC is controlled to supply the charging current to a battery, and a control unit is used to generate a PWM signal with a duty cycle, and a filter unit is used to convert the PWM signal into a voltage signal to be supplied to the charging IC, and the control unit determines whether a current of a battery detected by the battery status detection unit reaches a regular current, so that a PWM signal with a duty cycle greater than the previous duty cycle by a default increased cycle is provided if the detected current has not reached the regular current. Thus, the feature of the PWM signal is used to set the charging current according to the capacity of the battery automatically.