一种次级侧控制软开关15W反激变换器设计  

Design of a secondary side controlled soft-switching 15 W flyback converter

作　　者：陈瑾怡 王俊峰[1] 王凯[1] CHEN Jinyi;WANG Junfeng;WANG Kai(Xi'an Microelectronics Technology Institute,Xi'an 710054,China)

机构地区：[1]西安微电子技术研究所,陕西西安710054

出　　处：《微电子学与计算机》2025年第2期103-111,共9页Microelectronics & Computer

摘　　要：传统的反激变换器多采用初级侧控制方法,即通过光电耦合器传递反馈信号的方法,由于光电耦合器的电流传输比与温度以及使用时间成负相关,导致电路可靠性下降,环路增益变差;近年来提出的原边反馈控制方法,即通过引入辅助绕组反馈输出电压,这种采样方式的误差较大,而且控制方法更为复杂。因此本文提出了次级侧控制策略,输出电压反馈误差信号可以直接接入脉宽控制电路,避免引入光电耦合器与辅助绕组,减小变换器面积与成本。针对较高工作频率下硬开关方式产生的开关损耗呈指数增长,以及电磁噪声更加严重的问题,本文采用一种软开关方法,通过对次级侧整流开关管注入软开关的驱动窄脉冲信号,实现初级侧功率开关管的零电压开通。综上,本文提出一种次级控制软开关反激变换器的设计方案,设计出一款典型输入28 V,输出5 V/15 W的原理样机,通过对样机的测试验证,得出本文提出的控制方法,能够在全电压范围内和全负载范围内实现零电压开通,使反激变换器在满载状态下效率达到90.8%,相较于传统控制方法效率提升了5%~6%。The traditional flyback converter mostly uses the primary side control method,that is,the feedback signal is transmitted through the photoelectric coupler.Because the current transmission ratio of the photoelectric coupler is negatively correlated with the temperature and the use time,the circuit reliability is reduced and the loop gain is worse.In recent years,the primary side feedback control method is proposed by introducing auxiliary windings to feedback the output voltage.This sampling method has a large error,and the control method is more complex.Therefore,the secondary side control strategy is proposed in this paper.The output voltage feedback error signal can be directly connected to the pulse width control circuit,avoiding the introduction of photoelectric coupler and auxiliary windings,and reducing the area and cost of the converter.Aiming at the problem that the switching loss caused by the hard switching increases exponentially and the electromagnetic noise is more serious at higher operating frequency,a soft switching method is adopted in this paper.By injecting the soft switching drive pulse signal into the secondary side rectifier MOSFET,the primary side MOSFET is turned on at zero voltage.In summary,this paper proposes a design scheme of secondary control soft-switching flyback converter,and designs a typical input 28 V,output 5 V/15 W principle prototype.Through the test and verification of the prototype,it is concluded that the control method proposed in this paper can realize zero voltage switching in the full voltage range and full load range.The efficiency of the flyback converter reaches 90.8%at full load,which is 5%-6%higher than that of the traditional control method.

关 键 词：反激变换器 次级控制 软开关 同步整流 

分 类 号：TN45[电子电信—微电子学与固体电子学]