Solar Charging Device Startup for Overdischarged Batteries
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Solution Overview
Problem
Conventional photovoltaic charging devices face challenges in starting the control circuit when a lithium-ion battery, used as a secondary battery, is in an overdischarged state, as it cannot supply the necessary power to initiate charging, and adding a separate power supply compromises portability.
Innovation Solution
A charging device with a charging control unit, a step-up power supply, and a start-up control unit that boosts solar-generated power to start the charging control unit without an external power source, allowing for appropriate charging even when the secondary battery is overdischarged, using PWM control and smoothing to manage voltage and current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a lithium-ion battery is used as the secondary battery to reduce weight and improve portability, then the weight of the charging device is reduced, but the battery may become overdischarged and unable to supply power to start up the control circuit
Solution Approach 1:
The step-up power supply performs preliminary action by boosting the voltage from the solar cell before the control circuit needs to operate. This preliminary voltage boosting ensures that even when the battery is overdischarged, there is sufficient voltage to start up the control circuit, thus resolving the contradiction between using lightweight lithium-ion batteries and maintaining reliability for circuit startup.
Solution Approach 2:
The step-up power supply acts as an intermediary between the solar cell and the control circuit. It mediates the voltage mismatch by boosting the solar cell output to a level sufficient for control circuit operation, enabling the system to function even when the battery cannot provide adequate voltage, thus maintaining reliability without adding weight.
2Reliability
If another power supply is included to start up the control circuit when the battery is overdischarged, then the control circuit can be started, but the portability of the charging device is compromised
Solution Approach 1:
The step-up power supply serves multiple functions: it boosts voltage for control circuit startup, and continues to provide power conditioning during normal operation. This multi-functionality eliminates the need for a separate dedicated startup power supply, maintaining portability while ensuring reliability for circuit startup even when the battery is overdischarged.
Solution Approach 2:
The step-up power supply enables the system to be self-sufficient by using the solar cell's output to bootstrap the entire system. When the battery is overdischarged, the step-up power supply allows the control circuit to start up without external assistance, and the system then becomes self-service capable, eliminating the need for additional power supply components that would compromise portability.
3Productivity
If PWM control is used to control the electric power from the solar cell, then the charging efficiency is improved, but the control circuit requires stable power supply to operate
Solution Approach 1:
The step-up power supply performs preliminary voltage boosting and stabilization before the PWM control operates. This preliminary action ensures that the control circuit receives stable power even when the solar cell output or battery voltage varies, enabling efficient PWM control to function reliably and maintain both charging efficiency and control circuit 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
Enables the charging device to start and maintain charge operations without a separate power supply, ensuring the lithium-ion battery can be charged effectively while preventing heat generation due to lithium metal deposition, thus enhancing portability and reliability.
Implementation Method 1
a charging device to charge a lithium-ion battery with electric power generated by a solar cell
Implementation Method 2
The step-up power supply boosts the electric power from the solar cell
Data Source
AI summary
A charging device is provided, which is capable of starting up a control circuit without any separate power supply so as to start an appropriate charge operation even when a secondary battery is in an overdischarged state. A charging device to charge a secondary battery with electric power generated by a solar cell includes: a charging control unit that controls the electric power generated by the solar cell to have a current value and/or a voltage value suitable for charging, and that supplies the controlled electric power to the secondary battery; and a start-up control unit that supplies, to the charging control unit, a boosted power source by boosting the electric power from the solar cell when charging is started, and that starts up the a charging control unit.