Flyback Converter Secondary Synchronous Rectification
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Solution Overview
Problem
Traditional flyback power converters with multiple outputs face challenges in stabilizing output voltages efficiently while minimizing power consumption, as they rely on linear voltage regulators that consume excess power due to high winding voltages.
Innovation Solution
A flyback power converter with multiple outputs incorporates a transformer, output circuits, and a secondary side synchronous rectification controller, allowing energy transfer between output capacitors through a rectifying switch, controlled by a synchronous rectification controller to regulate voltage levels without linear regulators, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear voltage regulators are used to regulate output voltage at secondary output terminals, then output voltage stability is improved, but power consumption increases due to high winding voltages
Solution Approach 1:
The patent replaces linear voltage regulators with a synchronous rectification controller that uses PWM-controlled MOSFETs to achieve voltage regulation. This substitution of the regulation mechanism eliminates the inherent power loss of linear regulators while maintaining output stability through active switching control
Solution Approach 2:
The patent changes the regulation approach from linear voltage dropping to synchronous switching rectification. By controlling the conduction time of rectifying switches based on detected conduction periods, the system achieves voltage regulation through parameter control (switching timing) rather than resistive voltage dropping, significantly reducing power consumption
2Reliability
If high winding voltage is applied to ensure sufficient voltage headroom for linear regulators, then output voltage regulation capability is improved, but power consumption increases
Solution Approach 1:
The patent replaces the linear regulator system with a synchronous rectification system using MOSFETs as controlled switches. This substitution eliminates the resistive power loss inherent in linear regulators while maintaining the ability to regulate output voltage through controlled switching
Solution Approach 2:
The system uses the transformer's own winding voltage and the synchronous rectification process to directly achieve voltage regulation without requiring excessive voltage headroom. The detected conduction period information is used to control switch timing, allowing the system to operate efficiently at lower voltage margins
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
This solution effectively stabilizes output voltages across multiple terminals, enhances energy efficiency by eliminating the need for high-power linear regulators, and adapts to varying load conditions, ensuring stable operation with reduced power consumption.
Implementation Method 1
The transformer has a primary side winding, a first output winding and a second output winding
Implementation Method 2
The secondary side synchronous rectification controller controls conduction time of the second rectifying switch according to a detecting signal indicative of a secondary side conduction period. Thus, the electric energy is transferred between the first output capacitor and the second output capacitor through the second output winding and the second rectifying switch
Data Source
AI summary
A flyback power converter with multiple outputs is disclosed. The flyback power converter has a transformer, a first output circuit, a second output circuit, and a secondary side synchronous rectification controller. The transformer has a primary side winding, a first output winding, and a second output winding. The first output circuit has a first output capacitor for storing electric energy from the first output winding. The second output circuit has a second rectifying switch and a second output capacitor. The second output capacitor is utilized for storing the electric energy from the second output winding. The secondary side synchronous rectification controller controls the conduction time of the second rectifying switch according to a detecting signal of a secondary-side conduction period. The electric energy in the first output capacitor may be transferred to the second output capacitor through the second output winding and the second rectifying switch and vice versa.