| Cascade is a typical connection method of each converter in distributed power systems. The DC converter cascade has been wildly used in the field of motherboard power supplying, communication power supplying and power adapters. Cascade has played an important role in the transformation of energy and the improvement of efficiency. Meanwhile, there are some problems about stability in the DC converter cascade as the interaction between the converters. In this paper, we study to solve the problem about stability in the DC-DC converter cascade.First, it introduces the small-signal converter model employed to derive the input and output impedances. To verify theoretical results,simulations are done on a voltage Mode controlled buck converter in PSIM software. Next, it creates a two-port small-signal model of a cascade system and derives the stability criterion. The parameters of the cascade converter according to the requirements of the subject and the stability criterion has been designed in this paper. The factor that affects the input and output impedance of converter is also studied in MATLAB software. Finally, this article presents primary research program in face of the stability problem of a converter whose internal parameters can not be changed. Through the virtual impedance, the magnitude and phase of the input impedance of the load converter can be modified to ensure the whole cascaded system work well. |
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