Secondary Synchronous Rectification Control Module for Flyback Power Supplies
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Solution Overview
Problem
Flyback power supply systems require complex control circuits to accurately control synchronous rectifiers, leading to inefficiencies and increased costs due to the difficulty in predicting the proper time to enable and disable the rectifier.
Innovation Solution
A secondary synchronous rectification control module that uses a timer to determine the on-time for synchronous rectification based on voltage comparison with a reference voltage, allowing for continuous current mode operation and reducing the need for complex circuitry by controlling pulse width modulation on the primary side of a quasi-resonant controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed frequency clock is used to predict the timing for enabling/disabling the synchronous rectifier, then the control can be implemented, but complicated circuitry is required which increases system cost
Solution Approach 1:
The patent replaces the mechanical/electronic clock-based timing system with a magnetic field sensing system. The synchronous rectifier controller detects the magnetic field collapse of the primary coil to determine when to enable/disable the synchronous rectifier, eliminating the need for complex clock prediction circuitry and reducing system cost while maintaining accurate timing control.
2Loss of energy
If burst-mode operation is used to reduce power dissipation during light load conditions, then power efficiency is improved, but it becomes difficult to accurately predict the proper time to enable and disable the synchronous rectifier
Solution Approach 1:
The patent implements a feedback mechanism where the synchronous rectifier controller continuously monitors the magnetic field status of the primary coil. By detecting when the magnetic field collapses, the controller receives real-time feedback about the primary coil's state, allowing it to accurately determine the proper timing for enabling and disabling the synchronous rectifier during burst-mode operation, thus maintaining both energy efficiency and timing precision.
3Measurement precision
If complex control circuits are used to accurately control synchronous rectifiers in flyback power supply systems, then control accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent replaces complex electronic control circuits with a magnetic field-based detection system. The synchronous rectifier controller uses magnetic field sensing to accurately detect the primary coil's magnetic field collapse, providing precise control timing without requiring complex prediction algorithms or additional control circuitry, thus achieving high control accuracy with simplified circuit design.
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 simplifies the control circuitry, improves efficiency by accurately controlling the synchronous rectifier, and reduces costs by eliminating the need for complicated circuitry, while ensuring continuous conduction mode operation and preventing primary side inductance saturation.
Implementation Method 1
the current through a primary coil of a transformer was terminated in order to cause the magnetic field to collapse and couple power to a secondary inductor of the transformer
Implementation Method 2
cause the magnetic field to collapse and couple power to a secondary inductor
Data Source
AI summary
In accordance with an embodiment, a method for controlling a circuit includes controlling pulse width modulation on a primary side of a quasi-resonant controller to achieve continuous current mode operation from a synchronous rectification controller on a secondary side.