A Split-Winding Current-Fed Three-Level Multiport Converter With Auxiliary Inductor for DC Micro-Grid Application

Multilevel multiport dc–dc converters offer superior voltage-blocking capability, larger step-up ratios, and increased degrees of freedom compared to traditional two-level (2L) multiport converters (MPC) making them particularly suitable for connecting energy storage (ES) devices to dc micro grids. This article introduces a current-fed three-level (3L) triple active bridge (TAB) dc–dc converter with auxiliary inductor which uses a split winding (SW) high-frequency transformer. Detailed transformer modeling has been presented and its advantages over traditional transformer has been discussed. Power flowthrough different ports has been analyzed using Fourier series of port voltages which remain valid over the entire range of duty cycle and phase shift angle. Effect of different variables like the duty cycle and phase shift angle on power flow and zero voltage switching (ZVS) operation has been presented. The performance of the proposed converter structure has been validated on a laboratory prototype operating at 1.6 kW power output and 100 kHz switching frequency, achieving voltage conversion from 90 to 650 V. The prototype demonstrated a peak efficiency of 96.8% during forward power flow (FPF) which is at least 4% more than the conventional voltage-fed (VF TAB) converter.