Resonant Flyback Converter for Zero-Voltage Switching
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Solution Overview
Problem
Conventional flyback converters require an auxiliary winding and additional voltage regulation stages, leading to complex system structures and poor conversion efficiency.
Innovation Solution
A flyback converter with a resonant loop circuit and a power supply device that includes a controllable switching transistor and a charging capacitor, allowing for zero voltage switching of the main switching transistor and optimizing power supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an auxiliary winding and additional voltage regulation stages (LDO or DC-DC converter) are used, then the output voltage can be regulated, but the system structure becomes complex and conversion efficiency deteriorates
Solution Approach 1:
The patent combines the auxiliary winding power supply function with the main switching circuit by using the resonant loop circuit formed by the first capacitor, primary side winding, and second switching transistor to directly generate the supply voltage for the main switching transistor. This eliminates the need for separate LDO or DC-DC converter stages, thereby simplifying the system structure while maintaining voltage regulation capability through the resonant circuit's inherent characteristics
Solution Approach 2:
The resonant loop circuit serves multiple functions: it provides power supply to the main switching transistor, enables zero voltage switching, and regulates voltage through its resonant characteristics. The auxiliary winding is integrated into this multi-functional circuit, allowing it to contribute to both power transfer and power supply generation, thereby reducing the need for dedicated voltage regulation components
2Loss of energy
If conventional power supply methods are used, then the system structure is simpler, but conversion efficiency deteriorates and zero voltage switching cannot be achieved
Solution Approach 1:
The resonant loop circuit pre-charges the first capacitor to a voltage higher than the input voltage before the main switching transistor turns on. This preliminary action ensures that when the main switching transistor switches, the voltage across it is zero, enabling zero voltage switching and eliminating switching losses. The circuit prepares the necessary voltage conditions in advance to achieve efficient switching
Solution Approach 2:
The patent utilizes resonant oscillation in the loop circuit formed by the first capacitor, primary side winding, and second switching transistor. This resonant vibration allows the circuit to naturally oscillate at its resonant frequency, enabling the voltage across the main switching transistor to reach zero before switching occurs, thereby achieving zero voltage switching and significantly improving conversion efficiency
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 enhances conversion efficiency and simplifies system structure by enabling zero voltage switching, reducing switching losses, and optimizing power supply efficiency.
Implementation Method 1
a resonant loop circuit is formed by connecting the first capacitor to a primary side winding of the transformer and the second switching transistor
Implementation Method 2
the charging capacitor is charged and stores energy
Implementation Method 3
a transformer, wherein a resonant loop circuit is formed by connecting the first capacitor to a primary side winding of the transformer
Data Source
AI summary
Disclosed is a flyback converter and a control method thereof. The flyback converter includes a first switching transistor, a second switching transistor, a transformer, a first capacitor, a power supply device. A resonant loop circuit is formed by connecting the first capacitor to a primary side winding of the transformer and the second switching transistor. In a first operating mode, a controllable switching transistor of the power supply device is turned on before the second switching transistor is turned off, and after the second switching transistor is turned off, the charging capacitor is charged and stores energy. In a second operating mode, before the first switching is turned on, the controllable switching transistor is turned on, and the charging capacitor is charged and stores energy. The conversion efficiency of the power supply is enhanced while enabling the first switching transistor to operate under zero voltage switching, thereby reducing switching losses.