The book focuses on the topology and modulation of non-isolated and isolated high-power DC/DC converters. Firstly, two non-isolated soft-switching resonant step-up structures are proposed. Secondly, the auxiliary-and-main-currents-diversion idea is introduced to significantly reduce the switching loss of the converter, based on which a series of isolated ZCS resonant converters is proposed. Thirdly, the transformer magnetic flux density of isolated resonant converter is totally studied and an asymmetric pulse frequency modulation is proposed to avoid the transformer saturation problem. Finally, three different types of ±35kV/500kW DC grid-connected converters are successfully demonstrated in Zhangbei Renewable Energy Base of China.