An Automated Semi–symbolic State Equation Generation Method for Simulation of Power Electronic Systems

Computer-aided analysis is playing an important role in the design and control of power electronic systems. A discrete-state event-driven (DSED) framework with state-space modeling has been proposed recently for accurate and efficient off-line simulation. Nevertheless, automated equation formulation for arbitrary circuits is also required to develop the DSED framework toward general simulation software. However, the traditional state equation generation method is very time-consuming, especially for large-scale systems due to the variable topologies brought by switching events. In this article, an automated semi-symbolic state equation generation method is proposed. Based on the switching function modeling of basic switching legs, an explicit function from switching states to state equation matrices is given, which reduces the computational cost without sacrificing any accuracy. The operating and topological characteristics of power electronics systems are utilized for further optimization. The proposed method greatly increases the simulation efficiency of power electronic systems, especially for large-scale systems. Two cases of the 2 MW 4-port solid-state transformers with different system scales are simulated with the proposed method under the DSED framework. About 700-fold and 1200-fold acceleration is achieved compared with one fast-speed commercial software, where the proposed method contributes 50-fold and 110-fold acceleration in the two cases, respectively.