Three-Output Flyback Converter with Synchronous Rectification for Improving Cross-Regulation and Efficiency

Abstract

This paper proposes a single stage alternating current/direct current (AC/DC) flyback converter which contains three output windings with synchronous rectification (SR) function to achieve better cross-regulation and efficiency. Because the three output windings are stacked in a series structure and use synchronous rectification instead of diode rectification, the forward conduction loss of the diode can be eliminated, and the current of each winding can flow bilaterally. Therefore, the energy of leakage inductance can be dissipated through heavy load winding without transient overvoltage in light load winding. Compared with existing methods in the literature, the proposed converter can be realized by simple analog IC with fewer winding turns. Finally, under the extreme load imbalance condition, the cross-regulation is still within ±2.26%. The maximum efficiency of the proposed converter reaches 87%, which is about 3% higher than the conventional Schottky diode solution’s efficiency. The circuit structure and operation principle are described. A practical prototype and experiment results are implemented to verify the feasibility of the proposed converter.

Analysis and Design for Output Voltage Regulation in Constant-on-Time-Controlled Fly-Buck Converter

“…where t on is the on-time determined by the COT generator. As for Q 2 , using Equations ( 6), (8), and ( 9) and assuming that L m is large enough in flyback mode, i c1 (t) in the time interval [t 1 , t 2 ] is obtained as:…”

“…Multi-output converters can be utilized when different types of output voltages are required in power conversion applications. As the need for multi-output power supply in various industrial applications such as telecommunication equipment and medical devices increases, studies on multi-output converters with simple structure, high efficiency, and improved cross regulation characteristics are being actively conducted [1][2][3][4][5][6][7][8]. As part of these studies, a new multi-output converter called fly-buck converter has been proposed in [9].…”

Primary-side control for the flyback AC–DC converter

“…Flyback topology in the same switching cycle, the original with vice and the inductance of the induced electromotive force polarity, will be adaptive to change and does not need extra inductance reset circuit (Chang et al, 2019). Therefore, the flyback converter has the advantage of simple structure compared with the forward converter (Tang et al, 2021a;Chen et al, 2021;Leng and Chiu, 2021;Wu et al, 2021).…”

A Dual-Mode Control Scheme to Improve Light Load Efficiency for Active-Clamp Flyback Converter

“…In this technique, a circuit loop, comprising an auxiliary switch (Q 2 ) and a capacitor (C clamp ), is added at the two terminals on the primary side of the transformer. This loop is used to perform ZVS at the main switch, improving converter efficiency and avoiding the high voltage spikes generated when the main switch is turned off [1][2][3][4][5][6][7]. However, conduction loss caused by resonant circulating current and additional switching in the Q 2 switch induces high power loss under light load [8].…”