Modeling and Nonlinear Dynamic Analysis of Cascaded DC–DC Converter Systems Based on Simplified Discrete Mapping
Chao Cheng, Fan Xie, Bo Zhang, Dongyuan Qiu, Wenxun Xiao, Huayv Ji
Abstract
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.