准谐振改进型SEPIC变换器建模与分析

凭借高电压增益及低电压应力的特点，改进型SEPIC变换器广泛地应用于光伏、不间断电源等领域。同时由于其具有良好的软开关特性，可应用于高频场合，以提升功率密度。为了拓宽负载变化范围，改善动态响应，其数学模型的建立至关重要。采用广义状态空间平均法，对基于开关电感的准谐振改进型SEPIC变换器进行建模，建立其对应的小信号模型，并得到系统输出的传递函数。使用K-factor的方法设计补偿器，优化系统的动态性能，设计恒流输出的数字控制实现方法，并通过实验进行了验证。

Modeling and Analysis of Quasi-resonant Modified SEPIC Converter

Owing to its characteristics of high voltage gain and low voltage stress, the modified SEPIC converter is widely applied in fields such as photovoltaic and uninterruptible power supply. At the same time, because of its satisfying soft switching characteristic, it can also be applied to high-frequency scenarios to improve the power density. To expand the load range and improve the dynamic response, the establishment of a mathematical model is important. In this paper, the generalized state-space averaging method is adopted to model a quasi-resonant modified SEPIC converter based on switched inductor, the corresponding small signal model is established, and the transfer function of system output is obtained. The K-factor method is used to design a compensator, thus optimizing the system''s dynamic performance. A digital control method of constant-current output was designed, which was further verified by experimental results.