Flyback Converter Control for Variable Output Voltage
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Solution Overview
Problem
Conventional flyback converter control schemes are inadequate for applications with variable output voltages, as they require constant turn-on time and dead time for the auxiliary switch, leading to increased complexity and obstacles in controlling variable dead time, especially at higher switch frequencies.
Innovation Solution
A method and apparatus for controlling a flyback converter that dynamically adjusts the turn-on time of the auxiliary switch and dead time based on input and output voltage signals, ensuring zero-voltage-switching (ZVS) of the main switch by sampling these signals and using proportional relationships to determine the turn-on time and dead time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If constant turn-on time and dead time are used for the auxiliary switch, then the control scheme is simple, but it is not suitable for applications with variable output voltages
Solution Approach 1:
The patent implements dynamic adjustment of the auxiliary switch turn-on time and dead time based on detected output voltage levels. The controller automatically varies these timing parameters to match different output voltage requirements, enabling the flyback converter to adapt to variable voltage applications while maintaining ZVS operation and efficiency
2Loss of energy
If variable dead time is implemented to optimize efficiency, then efficiency is improved, but transmission delay and parameter tolerance become huge obstacles
Solution Approach 1:
The patent employs a feedback mechanism where the controller detects the actual output voltage and uses this information to dynamically adjust the auxiliary switch timing parameters. This closed-loop control ensures that the variable dead time and turn-on time are precisely optimized for each operating condition while maintaining control reliability by continuously monitoring and adjusting based on actual system state
Data Source
AI summary
The present invention discloses a method and an apparatus for controlling a flyback converter, the flyback converter including a main switch, a transformer and an auxiliary switch. The method includes: obtaining a first voltage signal and a second voltage signal, the first voltage signal representing an input voltage of the flyback converter, and the second voltage signal representing an output voltage of the flyback converter; controlling turn-on of the auxiliary switch, wherein the turn-on time period of the auxiliary switch is determined according to the first voltage signal and the second voltage signal; and turning on the main switch at ZVS condition, wherein the main switch is turned on at the time delayed for a duration of a dead time after turning off of the auxiliary switch.