This book focuses on analysis, modulation, simulation, and prototype verification of the power electronic converters in advanced co-phase traction power supply systems. Firstly, the grid-connected characteristic is introduced in the grid-connected traction power supply system. Then, the detailed circuits analysis, control, and modulation of grid-connected three-phase converter, single-phase converter, clamped multi-level three-phase to single-phase converter, modular multi-level three-phase to single-phase converter, and two-phase to single-phase converter in advanced co-phase system are analyzed and discussed in different chapters separately. It's also serves as an excellent reference for the study and research of power electronics related specialties.