A modular DC solid state transformer for future onboard DC grid

Medium voltage DC (MVDC) grid has quite a lot advantages for the application of large power electric ships, while the DC breaker and DC distribution are the key equipment. Solid state transformer (SST) composed by power electronics transformer and high-frequency transformer has high power density and high efficiency, so it can be used for the power conversion from MVDC to low voltage DC or AC, especially as the development of wide-band gap devices with higher voltage, higher switching frequency with less conduction and switching loss. Several SST topologies suitable for onboard DC distribution are analyzed in this paper, then the control algorithm are proposed to realize DC bus equalization. Experimental results are proposed to verify the performance of the SST and control method.