Active Clamp Flyback Control for Leakage Energy Recovery
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Solution Overview
Problem
Existing active clamp flyback (ACF) control methods have a poor recovery effect on leakage inductance energy, leading to energy loss and inefficiency in power adapters.
Innovation Solution
A control method for an active clamp flyback converter that includes controlling the clamp switch to turn on during the demagnetization stage and turn off when the resonant current of the clamp capacitor and leakage inductance reaches a preset current threshold, optimizing the conduction time to improve energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an RCD absorption circuit is added to reduce voltage stress on the main switching transistor, then the voltage stress is reduced, but the leakage inductance energy is wasted through the resistor
Solution Approach 1:
The patent converts the harmful leakage inductance energy into useful energy by using the clamp switch and clamp capacitor to recover and store the energy during the demagnetization stage, then transferring it to the output side, transforming the previously wasted energy into a beneficial resource that improves overall efficiency
Solution Approach 2:
The patent changes the operating parameters of the clamp switch from fixed timing to dynamic timing based on detecting the resonant current threshold, optimizing the energy recovery process by adjusting the turn-off timing to coincide with when the resonant current reaches the preset threshold, thereby maximizing energy recovery while maintaining voltage protection
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 control method significantly improves the recovery efficiency of leakage inductance energy, reducing core loss, rectification loss, and turn-off loss, thereby enhancing the overall efficiency and power density of the active clamp flyback converter.
Implementation Method 1
the resonance between the leakage inductance of the primary side circuit and a junction capacitance of the switching transistor (such as a MOS transistor) of the primary side circuit causes the drain of the main switching transistor to generate a high frequency voltage spike
Data Source
AI summary
The present disclosure provides an active clamp flyback converter and a control method, and relates to the technical field of converter. The control method includes: in response to that an input voltage of the active clamp flyback converter is less than a preset voltage threshold, or the input voltage of the active clamp flyback converter is less than a product of an output voltage of the active clamp flyback converter and a turns ratio of the transformer, in a same switching cycle, controlling the clamp switch to turn on when the transformer is in a demagnetization stage; and controlling the clamp switch to turn off when a resonant current of the clamp capacitor and a leakage inductance of the transformer reaches a preset current threshold.