Abstract: For the mutual coupling problem of flying capacitor voltage and output voltage in three-level Buck converter, decoupling technology is used to design controllers to control two closed loops. In order to reduce the sensitivity to parameter variations and load disturbances, a Sliding Mode Controller based on PWM（PWM-SMC） is designed to control output voltage. Simulation results show that, comparing to the traditional PWM controller, the proposed controller not only controls effectively the flying capacitor voltage, but also shortens overshoot of output voltage and cuts down time of adjustment process.

Key words: three-level converter, decoupling control, sliding mode control, Pulse Width Modulation（PWM）

摘要： 针对Buck三电平变换器飞跨电容电压闭环与输出电压闭环相互耦合的问题，利用解耦控制技术分别独立地设计控制器对两个闭环进行控制。其中，为了降低对参数变化和负载扰动的敏感性，设计基于PWM的滑模变结构控制器对输出电压进行控制。仿真试验结果表明，与传统PWM控制器相比，该方法在保持对飞跨电容电压进行有效控制的同时能减小输出电压的超调量，缩短调节时间。

关键词: 三电平变换器, 解耦控制, 滑模变结构控制, 脉宽调制