说明：  以双向DC-DC变换器为例，通过双向控制模型的分析，采用PID 补偿环节的单电压闭环实现了BDC系统闭环稳定。
(Bi-directional DC-DC converter, for example, through the analysis of the two-way control model, the single-voltage closed-loop PID compensation link to achieve a the BDC system closed-loop stable.)