Modeling and Nonlinear Dynamic Analysis of Cascaded DC-DC Converter Systems Based on Simplified Discrete Mapping

摘要

As a basic structure of the distributed power systems, cascaded dc-dc converter systems have attracted a lot of attention. However, due to the interaction between the subconverters, classic methods for modeling cascaded systems are either not accurate enough, such as state-space averaging model, or not simple enough, such as discrete-time mapping model, especially the systems with different switching frequencies. To overcome this drawback, a simplified discrete-time mapping modeling method for cascaded dc-dc converter systems is proposed in this article. Based on the idea of state-space average, the original problem is simplified to modeling cascaded dc-dc converter systems with the same switching frequencies. The proposed method is able to predict the dynamic properties of the system at all stages, such as slow-scale and fast-scale instabilities. Then, two-stage cascaded boost converter with different switching frequencies under peak current double loop control is taken as an example to present the simplified discrete-time mapping model. Finally, the effectiveness of the proposed method is verified by simulations and experiments.

关键词