谐振电容电压反馈单输入多输出r反激式变换器

摘要

为减少小功率供电电源的器件使用数量、降低成本和提高变换效率,提出一种谐振电容电压反馈控制的不对称半桥反激式变换器.采用一次侧谐振电容电压反馈控制方式,简化了隔离型单输入多输出变换器的控制结构;采用恒定导通时间控制器,从而省去反馈补偿网络电路的设计;反馈信号取自一次侧谐振电容电压,具有反馈电压纹波大的特点,这会引起恒定导通时间控制出现脉冲破裂现象,变换器不能稳定工作.为抑制谐振电压反馈纹波大引起脉冲破裂的问题,采用纹波补偿恒定导通时间控制抑制反馈信号的电压纹波,从而使变换器工作稳定.最后通过实验样机验证了理论分析及设计方法的可行性.%A resonant capacitor voltage feedback control method for an asymmetrical half-bridge flyback converter is proposed in this paper. It can reduce the number of devices, save the costs and improve the efficiency in low power supply applications. By using this control method, the control structure of the isolated single-input multi-output converter is simplified. Moreover, there is no compensating circuit for the designed constant on-time controller. Since the feedback voltage signal for the control strategy is taken from the primary side resonant capacitor, it has large voltage ripple resulting in the pulse bursting phenomenon of constant on-time control, which makes the converter unstable. To restrain the pulse bursting phenomenon caused by the large voltage ripple, the constant on-time control with ripple compensation is used to suppress the feedback signal voltage ripple. Thus, the stability of the converter is guaranteed. Finally, the experimental prototype has verified the theoretical analysis and designing method.