A START-UP METHOD FOR A SPEED SENSORLESS STATOR-FLUX-ORIENTED VECTOR-CONTROLLED INDUCTION-MOTOR DRIVE

This letter describes a zero-speed start-up method of a speed sensorle ss stator-flux-oriented direct vector-controlled induction motor drive with the help of a machine current model that does not use any speed signal. The machine starts smoothly with vector control at finite deve loped torque and then transitions to the standard direct vector-contro l mode with the voltage model signals as the speed begins to develop. The direct vector-control mode with voltage model uses programmable ca scaded low-pass filters for flux-vector synthesis [2] and enables the drive to operate from zero speed to field-weakening mode. As the drive speed falls to zero, the drive again transitions to start-up mode, so that it can be smoothly started again. The performance of the start-u p scheme has been verified on a 100-kW electric vehicle drive.