Research on Control Strategy for Secondary Resonant Current Suppression Based on Single-Phase AC-DC-AC Converter

Railway traction power supply systems typically employ energy dispatching equipment (EDE) based on an AC-DC-AC topology for power quality management. Due to the single-phase rectifier topology within the EDE, the intermediate DC voltage inherently exhibits secondary ripple, which needs to be suppressed using additional filtering hardware. A phase difference in grid voltages between both ends of a converter can create power flow across these ends, leading to an increase in secondary resonant current. This phenomenon potentially results in overheating or even burnout of the main circuit. To address this issue, this paper proposes a control strategy that supports the active regulation of reactive power to suppress secondary resonant current. By constraining the variation range of the power factor and progressively injecting inductive reactive power, the proposed method effectively mitigates resonant current. Simulation and experimental results demonstrate the validity and feasibility of the proposed strategy in significantly reducing secondary resonant current.