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

Abstract

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 paper proposes a unified real-time simulation method of series-parallel DC/DC conversion systems, which unifies the input-series-output-series (ISOS), input-series-output- parallel (ISOP), input-parallel-output-parallel (IPOP) and input-parallel-output-series (IPOS) 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 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 250ns time-step on Xilinx K-7 Series FPGA, which verifies the accuracy and simulation efficiency of the unified model.