Design of a High Frequency Four Port Transformer for DC/DC Converters

Abstract

Large scale integration of renewable energy systems (RES) and energy storage systems (ESS) demands a better connectivity between distributed sources and loads. Multi-port solid state transformer (MPSST) plays a critical role as a joint node to integrate RESs, ESSs, utility grid, and loads. MPSST offers several advantages including independent power flow control on each port, voltage or current regulations, compactness and portability, and galvanic isolation. This thesis seeks to address some of the remaining challenges of using MPSST. Operation of the converter in closed-loop with phase shift modulation is analyzed for a dual active bridge as the control building block and a four-port DC/DC converter as the MPSST in Ansys Simplorer. The high frequency transformer part was designed and modeled in Ansys Maxwell. The model is validated with FEA simulation and various metrics like flux density (B), current density (J), magnetic field intensity (H), core loss, winding loss were investigated for different operating conditions to evaluate the transformer performance. A co-simulation between the magnetic environment in Ansys Maxwell, and power electronics and control part in Ansys Simplorer, has been carried out to benefit from the utilization of the developed realistic high frequency transformer for the operation of the MPSST.