LED Power Supply Circuit With Trough-Charging Two-Stage Conversion
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Solution Overview
Problem
Existing power supply circuits for LED driving systems face challenges in achieving high conversion efficiency and integration, with single-stage Buck solutions being complex and inefficient, while single-stage linear solutions have low efficiency and are unsuitable for high-current applications.
Innovation Solution
A power supply circuit comprising a linear conversion circuit, a capacitor, and a DC-DC conversion circuit, where the linear conversion circuit charges the capacitor during trough periods of the rectified voltage, and the DC-DC conversion circuit performs power conversion using the capacitor voltage, with dynamic threshold adjustment to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single-stage Buck power supply solution is used, then conversion efficiency is improved, but circuit structure complexity increases and integration is hindered
Solution Approach 1:
The power supply circuit is divided into two stages: a linear conversion circuit for voltage pre-regulation and a Buck circuit for final voltage conversion. This segmentation allows each stage to perform its function optimally while maintaining overall system efficiency and reducing complexity compared to a single-stage solution.
Solution Approach 2:
The linear conversion circuit performs preliminary voltage conversion before the Buck circuit operates. By pre-regulating the voltage in the linear stage, the Buck circuit operates under more favorable conditions, achieving high efficiency while reducing the complexity of the switching stage.
2Loss of energy
If a single-stage Buck power supply solution is used, then conversion efficiency is improved, but integration capability deteriorates
Solution Approach 1:
Dividing the power supply into separate linear and Buck conversion stages enables independent optimization and integration of each module. The linear conversion circuit can be integrated with control circuits using simple pad structures, while the Buck circuit handles high-frequency switching, achieving both high efficiency and integrability.
Solution Approach 2:
The linear conversion circuit acts as an intermediary between the rectified voltage input and the Buck circuit. This intermediate stage simplifies the requirements for the Buck circuit and enables better integration with control circuits by providing a pre-regulated voltage level.
3Device complexity
If a single-stage linear power supply solution is used, then circuit structure simplicity is improved, but conversion efficiency deteriorates
Solution Approach 1:
The power conversion is segmented into two stages: linear conversion for initial voltage regulation and Buck conversion for final efficient voltage transformation. This segmentation combines the simplicity of linear conversion with the efficiency of switching conversion, achieving both goals simultaneously.
Solution Approach 2:
The patent merges the advantages of linear power supply (simplicity, ease of integration) and Buck power supply (high efficiency) into a two-stage hybrid architecture, where each stage complements the other to achieve overall system optimization.
4Device complexity
If a single-stage linear power supply solution is used, then circuit structure simplicity is improved, but application scope deteriorates
Solution Approach 1:
By combining linear and Buck conversion circuits in a two-stage architecture, the system merges the simplicity and ease of integration of linear supplies with the high efficiency required for modern applications, thereby expanding the applicable scope to include both simple and demanding applications.
Solution Approach 2:
Segmenting the power conversion into two independent stages allows flexible configuration and adaptation to different application requirements. The linear stage provides simplicity for integration while the Buck stage provides efficiency for high-current applications, expanding overall system versatility.
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 proposed solution improves conversion efficiency to match or exceed that of single-stage Buck solutions, reduces packaging costs through single-pad frame integration, and minimizes energy storage device size, thereby achieving cost reduction, improved integration, and miniaturization.
Implementation Method 1
The rectifying circuit 1 rectifies the alternating current (AC) input signal from the AC power supply and outputs a rectified voltage VIN
Implementation Method 2
The linear conversion circuit 5 converts the rectified voltage VIN into a supply voltage Vo required by the wireless module 3
Implementation Method 3
The Buck circuit 2 converts the rectified voltage VIN into a supply voltage Vo required by the wireless module 3
Implementation Method 4
the single-stage Buck power supply solution shown in FIG. 1 has the advantage of higher conversion efficiency
Implementation Method 5
the linear conversion circuit controls the first rectified voltage to charge the first capacitor in a time period when the first rectified voltage is near a trough
Data Source
AI summary
A power supply circuit and a light-emitting diode (LED) driving system using the power supply circuit are provided. The power supply circuit includes a linear conversion circuit, a first capacitor, and a direct current-direct current (DC-DC) conversion circuit, where an alternating current input signal is rectified to form a first rectified voltage. The linear conversion circuit receives the first rectified voltage and has an output terminal connected to the first capacitor. After the power supply circuit is started, the linear conversion circuit controls the first rectified voltage to charge the first capacitor in a time period when the first rectified voltage is near a trough. The DC-DC conversion circuit receives a first capacitor voltage and performs power conversion to output a supply voltage. At least part of the linear conversion circuit and at least part of the DC-DC conversion circuit can be integrated with an LED driving circuit.