Flyback Converter Resonant Loop for Zero-Voltage Switching
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Solution Overview
Problem
Conventional flyback converters require an auxiliary winding and additional stages of low dropout regulators (LDO) or switching converters (DC-DC) for voltage regulation, leading to complex system structures and poor conversion efficiency.
Innovation Solution
A flyback converter with a resonant loop circuit and a power supply device connected at a common node of the switching transistors, which includes a controllable switching transistor and a charging capacitor, enabling zero voltage switching (ZVS) of the main switching transistor and optimizing power supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an auxiliary winding with LDO or DC-DC converter is used for voltage regulation, 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 function with the main power conversion circuit by using the resonant loop circuit formed by the first capacitor, second switching transistor, and transformer primary winding. This integration eliminates the need for separate LDO or DC-DC converter stages, thereby reducing system complexity while maintaining voltage regulation capability through the resonant oscillation mechanism.
Solution Approach 2:
The resonant loop circuit serves multiple functions: it provides voltage regulation, enables zero voltage switching for the main transistor, and supplies power to the control circuit. This multi-functionality replaces what would traditionally require separate auxiliary circuits, thus simplifying the overall system structure while improving conversion efficiency.
2Device complexity
If conventional PWM or quasi-resonant flyback converters are used, then the converter structure is simpler, but conversion efficiency and switching performance deteriorate
Solution Approach 1:
The patent employs resonant oscillation in the loop circuit comprising the first capacitor, second switching transistor, and transformer primary winding. This resonant vibration enables zero voltage switching of the main transistor, significantly reducing switching losses and improving conversion efficiency while maintaining a relatively simple flyback converter structure.
Solution Approach 2:
The patent changes the operating parameters by introducing resonant oscillation at specific frequencies, transforming the conventional hard switching mode into soft switching mode. This parameter change enables zero voltage switching, reducing switching losses and improving efficiency without requiring complex additional circuitry.
3Extent of automation
If the main switching transistor is turned on without zero voltage switching, then the switching control is simpler, but switching losses increase and conversion efficiency deteriorates
Solution Approach 1:
The resonant loop circuit is designed to oscillate and prepare the voltage conditions before the main switching transistor is turned on. The first capacitor and second switching transistor create a resonant circuit that naturally brings the voltage to zero before the switching event, enabling zero voltage switching without complex control logic.
Solution Approach 2:
The resonant oscillation provides natural feedback that automatically controls the timing and conditions of the main transistor switching. The oscillating voltage and current in the resonant loop circuit create self-regulating conditions that enable zero voltage switching, reducing the need for complex external control mechanisms.
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 enhances the conversion efficiency of the flyback converter by enabling ZVS of the main switching transistor, reducing switching losses, and simplifying the system structure while maintaining efficient power supply.
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
Data Source
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AI summary
Disclosed is a flyback converter. 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.