Unified Real-Time Simulation Method for DC/DC Conversion Systems Consisting of Cascaded Dual-Port Submodules

The dc/dc conversion systems are constructed from multiple cascaded dual-port submodules in series and/or parallel at both the input port and output port. The complexity of the series-parallel structures brings great challenges to real-time simulation. This article proposes a unified real-time simulation method of series-parallel dc/dc conversion systems, which unifies the input-series-output-series, input-series-output-parallel, input-parallel-output-parallel, and input-parallel-output-series structures. First, based on the nodal analysis method, the dual-port equivalent model of each submodule in the series-parallel dc/dc conversion system is obtained. Second, by cascading each submodule, the unified form of the system's dual-port equivalent model of the series-parallel dc/dc conversion system is constructed. For the series connection, the port is equivalent to Thevenin's equivalent circuit. For the parallel connection, the port is equivalent to Norton's equivalent circuit. The real-time simulation model of a specific series-parallel dc/dc conversion system can be obtained by combining the input/output port equivalent circuits. Besides, the high-frequency waveforms of the internal circuit can also be obtained through parallel calculation steps. The real-time simulation of the proposed unified model is carried out with a 250-ns time step on a Xilinx K-7 series field-programmable gate array, which verifies the accuracy and simulation efficiency of the unified model.