基于三端等效电路模型的FB-ZVZCS变换器控制环路设计方法

Control Loop Design of FB-ZVZCS Converter Based on Three-terminal Equivalent Circuit Model

为保证平均电流型控制方式下输出宽范围可调电源的全局稳定性,采用新型的三端等效电路模型对系统进行小信号建模,避免了传统平均模型不能预测次谐波振荡的问题。基于该模型给出了比例积分型电流补偿器的设计方法,获得良好的电流控制特性;分析了稳态工作点对系统控制环路设计的影响,给出了适合宽变工作点条件下电压外环的设计方法,在保证全局稳定性的同时,系统能获得更宽的控制带宽;利用该方法对一台最大电流4A、输出电压50~600 V连续可调的FB-ZVZCS变换器进行控制环路设计。实验结果表明,变换器在各稳态工作点具有良好的稳定性和动态特性,验证了设计方法的正确性。

In order to achieve the global stability of wide-range output power supply with average current mode control, the system＇s small-signal model was modeled by the novel three-terminal equivalent circuit model, this model can predict the sub-harmonic oscillation while average model can＇t. A new method was proposed for PI-type current compensator to obtain good current regulation. This paper analyzed the effect of steady working points to the control loop system design, and presented a proposed voltage compensator design method suiting for wide-range variable working conditions. Following the design method, the system can not only ensure the global stability but also achieve wide control bandwidth. The control loop design method was applied to a continuously adjustable FB-ZVZCS converter, which maximum current is 4 A, output voltage range is from 50 V to 600 V. The experimental results show that the converter has good stability and dynamic characteristics in all steady working points, and verify the validity of the design method.