Design and Implementation of a Medium Voltage, High Power, High Frequency Four-Port Transformer

With the growth in penetration number and power level of renewable energy resources, the need for a compact and high efficient solid state transformer becomes more important. The aim of this paper is to design a compact solid state transformer for microgrid application. The proposed transformer has four ports integrated on a single common core. Thus, it can integrate different renewable energy resources and energy storage systems. The transformer is operating at 50kHz switching frequency, and each port can handle 25kW rated power. In this paper, the ports are chosen to represent a realistic industrial microgrid model consisting of grid, energy storage system, photovoltaic system, and load. The grid port is designed to operate at 4160V AC, while the other three ports operate at 400V. Moreover, the grid, energy storage, and photovoltaic ports are active ports with dual active bridge topologies, while the load port is a passive port with full bridge rectifier one. In this paper, an extensive and complete design and modeling of the entire solid state transformer is presented. The proposed design is first validated with simulation results, and then the proposed transformer is implemented. Some preliminary experimental tests are also performed and the obtained results are reported.