The traction power supply network operates in a single-phase mode, and the converter on the traction side features a single-phase topology. Single-phase conversion circuits are widely utilized in various applications, such as power factor correction (PFC) and single-phase PWM converters (Zheng 2009; Xu 2013). To align with the traction network side, which typically operates at high voltages of up to 25 kV and supports traction load power ranging from several megavolt-amperes to tens of megavolt-amperes, most power converters for traction applications are designed with high-voltage, high-power single-phase conversion circuits. Applicable conversion circuit topologies include the single-phase two-level H-bridge, single-phase three-level H-bridge, and single-phase cascaded multilevel configurations. This chapter examines the aforementioned single-phase AC-DC conversion topologies and their operating principles. It also discusses the modulation and control strategies for typical single-phase converters, analyzes the unique characteristics of DC voltage ripple inherent to single-phase AC-DC topologies, and explores control methods to mitigate the effects of DC voltage ripple.