图腾柱功率因数校正器的二自由度控制分析

Analysis of Two-Degree-of-Freedom Control over Power Factor Corrector

TPFC一般采用一自由度输出电压控制,在负载变化时输出电压动态特性较差,且启动过程存在明显超调。本文在推导TPFC双闭环控制结构基础上,引用了负载电流前馈控制和输出电压反馈补偿控制,构成两种二自由度(2DOF)控制结构。仿真分析表明,负载电流前馈型2DOF控制可以有效抑制负载变化引起的输出电压波动,但启动过程超调明显;输出电压反馈补偿型2DOF控制可以实现输出电压无超调启动,但是抑制负载变化的能力较差;综合负载电流前馈型和输出电压反馈补偿型的2DOF控制获得满意的输出电压控制效果,表现为启动过程无超调和变载过程无波动。

Totem pole PFC(TPFC)generally adopts one-degree-of-freedom output voltage control.When the load changes,the dynamic characteristics of output voltage are poor,and there is obvious overshoot during the starting process.Based on the derivation of the double closed-loop control structure of TPFC,this paper introduces the load current feedforward control and output voltage feedback compensation control to form two two-degree-of-freedom(2DOF)control structures.The simulation results show that the load current feedforward 2DoF control can effectively suppress the output voltage fluctuation caused by load change,but the overshoot is obvious during start-up.The output voltage feedback compensation 2DoF control can realize the start without output voltage overshoot,but the ability to suppress load change is poor.The 2DOF control combining load current feedforward type and output voltage feedback compensation type obtains satisfactory output voltage control effect,which is that there is no overshoot in the starting process and no fluctuation in the load changing process.