Multi-Output Synchronous Flyback Converter Control Circuit
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Solution Overview
Problem
In multi-output flyback converters, the need for multiple switching control circuits for each secondary output rectifier increases costs and reduces efficiency due to higher component count and switching losses associated with traditional rectifying diodes.
Innovation Solution
A multi-output synchronous flyback converter design that employs low voltage rating controlled rectifiers and a single control circuit to drive multiple secondary synchronous rectifier MOSFETs, reducing the number of components and optimizing rectification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple switching control circuits are used for each secondary output rectifier, then each rectifier can be optimally controlled, but the component count increases and costs increase
Solution Approach 1:
The patent merges multiple secondary switching control functions into a single control circuit that can drive multiple synchronous rectifier MOSFETs. This is achieved by integrating multiple control channels within one control circuit, allowing it to generate gate drive signals for multiple MOSFETs simultaneously, thereby reducing the total number of control circuits while maintaining individual control capability for each rectifier.
Solution Approach 2:
The single control circuit is designed with multi-functionality to perform the control tasks of multiple rectifiers. It incorporates multiple control channels that can independently regulate different secondary outputs, making one circuit capable of performing what traditionally required multiple separate circuits, thus reducing component count while maintaining control performance.
2Device complexity
If traditional rectifying diodes are used, then the circuit is simple, but switching losses are high and efficiency is reduced
Solution Approach 1:
The patent replaces traditional passive rectifying diodes with active synchronous rectifier MOSFETs that are controlled by the control circuit. This substitution transforms the rectification mechanism from passive diode conduction to active MOSFET switching, enabling optimized switching timing and reduced conduction losses while maintaining circuit functionality. The MOSFETs operate in synchronous mode, turning on and off in coordination with the primary switch to minimize losses.
3Adaptability or versatility
If multiple control circuits are implemented, then each output can be independently regulated, but the overall system efficiency decreases due to higher component count
Solution Approach 1:
The patent combines multiple control functions into a single integrated control circuit that can independently regulate multiple secondary outputs. This merged circuit maintains the adaptability to control each output separately through its multiple control channels while reducing the total component count, thereby improving system efficiency by eliminating the redundant components and associated losses that would result from using multiple separate control circuits.
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 design minimizes secondary circuit losses and maximizes efficiency by using a single control circuit to drive multiple MOSFETs, reducing the component count and enhancing the overall performance of the flyback converter.
Implementation Method 1
the primary winding of the transformer is directly connected to the input voltage source and, correspondingly, the magnetic flux in the transformer core increases
Implementation Method 2
the diode 12 is in off-state since the voltage drop across its terminals is negative
Implementation Method 3
The use of controlled switches, such as power Mosfets and the like, allows minimizing the amount of the switching losses by optimizing, through suitable driving and control, the switching phase of the output rectifiers
Data Source
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AI summary
The present application concerns a multi-output synchronous Flyback converter. The Flyback converter comprises a primary controlled switch (24), a driver circuit (26), a transformer and a feedback circuit (27). The secondary side of the converter comprises a plurality of secondary windings (29, 30, 31), a plurality of controlled rectifiers (32, 33, 34), and a control circuit (35) adapted to sense the current and/or the voltage related to one of said controlled rectifiers and to generate a control signal for all said controlled rectifiers.