三级级联多母线直流系统稳定性分析及判据

Stability analysis and criterion of triple-stage cascade multi bus DC system

为了得到多级级联变换器系统稳定性判据,本文首先建立了多级级联DC-DC变换器的通用二端口小信号模型,并计算了其等效次回路增益,用于判断系统的稳定性。在此基础上,进一步推导了三级级联直流系统的稳定性条件,并与两个子系统进行了比较。得出结论是即使某些子系统不能单独稳定运行,但整个系统仍然可能是稳定。此外,根据推导出的稳定性条件,对现有的三级级联直流系统稳定性判据进行了统一解释,并提出了一种母线等效阻抗判据。

in order to obtain the stability criterion of multistage cascaded converter systems,Firstly,the generic two-port small-signal model of the multi-stage cascaded DC-DC converters is established and its equivalent minor loop gain is calculated,which can be used to assess system stability.On this basis,the stability condition of the triple-stage cascaded DC system is further deduced and compared with its two subsystems.The conclusion is that the whole system may be stable even if some of its subsystems cannot operate stably individually.Besides,according to the deduced stability condition,some existing stability criteria of the triple-stage cascaded DC system are explained uniformly and a bus equivalent impedance criterion(BEIC)is proposed.Finally,the case study and experiments are carried out to verify the correctness of theoretical analysis.