A novel startup scheme of stator-flux-oriented vector-controlled induction motor drive without torque jerk

This paper proposes a novel zero-speed startup scheme of a stator-flux-oriented speed-sensorless vector-controlled induction motor drive that does not generate any torque jerk. A programmable cascaded three-stage low-pass filter (LPF) method is used for flux vector estimation. Usually, a torque jerk is generated at the vector control transition due to time delay in developing the stator flux by the three-stage LPF. At standstill condition, an algorithm is derived that calculates the stator flux using only the stator currents. A feedforward control strategy of the stator flux is developed to eliminate the torque jerk during transition from the standstill mode to the vector control mode. The performance of the newly developed startup scheme has been verified by simulation and then experimentally on a 3-hp induction motor drive, where the control was implemented by a 32-bit TMS320C30-type digital signal processor. The performance of the drive was found to be excellent in both simulation and experiment.