A new type of unit power factor rectification based on single cycle control One-Cycle Control (OCC) was proposed. The circuit was powered by a downhole electric locomotive. The power supply was composed of a rectifier stage based on cascaded vienna rectifier and a transmission stage based on high-frequency isolated DC-DC converter. However, an overall control scheme was adopted to regulate the two stages. This simple control scheme could realize the unity power factor without involving any multipliers or input voltage sensors. Besides, the voltage pressure of the switches could be reduced by half due to the topology structure. The basic operating principles and the double-loop control strategy were analyzed in detail. The correctness of the proposed circuit and its corresponding control strategy was verified by simulation and experiment.