Solar Charging Circuit with Dynamic Voltage Tracking
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Solution Overview
Problem
Charging circuits for secondary batteries using solar batteries face inefficiencies due to voltage fluctuations with illumination intensity and temperature, requiring complex circuit configurations and suboptimal power delivery, especially when using multi-cell solar batteries with reduced aperture ratios and appearance issues.
Innovation Solution
A charging circuit with a DC/DC converter, switching transistor, inductor element, rectifier, and control circuit that adjusts the duty ratio and frequency of a pulse signal to match the solar battery's voltage, optimizing charging current and power delivery by sweeping reference voltages and transistor sizes for maximum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control is applied to stabilize input voltage at 0.5V regardless of illumination intensity, then voltage stability is improved, but maximum power output is not achieved
Solution Approach 1:
The patent implements dynamic tracking of the maximum power point by continuously adjusting the input voltage based on detected power levels. Instead of fixing the voltage at 0.5V, the system dynamically adapts the voltage to match the solar battery's optimal operating point under varying illumination conditions, thereby maintaining both stability and maximum power extraction.
Solution Approach 2:
The patent employs feedback control by detecting the power output of the solar battery and using this information to adjust the input voltage to the DC/DC converter. The control unit monitors the power level and modifies the operating voltage accordingly, creating a closed-loop system that maximizes power extraction while adapting to changing conditions.
2Loss of energy
If input voltage is adjusted according to temperature to maintain maximum power point, then power output efficiency is improved, but circuit complexity increases
Solution Approach 1:
The patent changes the operating voltage parameter based on temperature variations. The control unit detects temperature changes and adjusts the input voltage to the DC/DC converter accordingly, compensating for the temperature coefficient effect on solar battery voltage. This allows the system to maintain optimal power extraction across different temperatures without requiring complex hardware modifications.
3Power
If multi-cell solar battery structure is used to increase voltage output, then voltage is improved, but aperture ratio decreases and appearance deteriorates
Solution Approach 1:
The patent changes the electrical parameters (voltage and current) rather than the physical structure of the solar battery. By using a single-cell or fewer-cell configuration and adjusting the operating parameters through controlled voltage reduction and current increase, the system achieves the required power output while maintaining a high aperture ratio and better appearance.
Solution Approach 2:
The patent employs periodic pulse width modulation (PWM) to control the power transfer from the solar battery. By using periodic switching action with adjustable duty cycle, the system can regulate power output without increasing the physical size or number of cells, thereby maintaining high aperture ratio while achieving the desired voltage and current characteristics.
4Power
If voltage boosting is performed using DC/DC converter to charge lithium-ion battery, then charging capability is improved, but power loss in converter increases
Solution Approach 1:
The patent dynamically optimizes the operating point of the DC/DC converter by continuously adjusting the input voltage to match the solar battery's maximum power point. This dynamic adaptation minimizes the power loss in the converter by ensuring that the input side operates at peak efficiency, thereby improving overall charging capability while reducing energy waste in the conversion process.
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
The solution enables high-efficiency charging of secondary batteries by dynamically adjusting the charging current and power delivery, reducing charging time and power consumption, and optimizing the DC/DC converter's efficiency across varying conditions.
Implementation Method 1
a solar battery, and to charge a secondary battery using electric power received from the solar battery
Implementation Method 2
a DC/DC converter comprising a switching transistor, an inductor element, a rectifier element, and an output capacitor
Data Source
AI summary
A charging circuit receives electric power from a solar battery, and charges a secondary battery. A charging current detection unit generates a detection signal that corresponds to a charging current supplied from a DC/DC converter to the secondary battery. A control circuit generates a reference voltage that corresponds to the detection signal. A driving unit generates a pulse signal having a duty ratio that is adjusted such that the voltage output from the solar battery matches the reference voltage, and performs switching of a switching transistor according to the pulse signal. A control circuit adjusts the reference voltage such that the reference voltage becomes greater.