Design of traction power supply system for linear motor driven urban transit test line

A traction power supply system which adopted separately excited DC generator sets was designed. The desired output voltage was kept constant by regulating the rotary speed of induction motor and field current. In order to realize almost ripple-free operation in the entire speed range and achieve the position sensorless control, direct torque control based on space-vector modulation (DTCSVM) strategy based on mutual model reference adaptive system (mutual MRAS) was used for induction motor. DTCSVM is able to reduce the acoustical noise, the torque, flux, current, and speed pulsations during steady state. Mutual MRAS was adopted to implement a position sensorless DTC of an induction motor. Simulation and experiment on the traction power supply system indicates that the proposed control method produces better results than the classical DTC. The output voltage of the power supply system remains constant when load changes. The overall system performance was verified by experiments.