A full speed domain sensorless control scheme is proposed for the efficient drive system of the Fuxing six axle freight locomotive, which integrates pulse high-frequency injection technology and adaptive sliding mode observation principle. This scheme constructs a hybrid excitation model combining high-frequency carrier signals and low-frequency pulse signals, and introduces an extended state observer with fuzzy gain adjustment mechanism, effectively achieving high-precision dynamic estimation of rotor position information and speed state. The ground joint debugging test verification shows that this scheme can maintain extremely high speed control accuracy in a wide range of environmental temperature and harsh heavy-duty operating conditions, while significantly reducing the overall system failure rate. This achievement provides an important engineering practice reference example for achieving sensorless control of rail transit traction systems.