A Restart Strategy of a Rotating Induction Machine for Inrush Current Elimination

Aiming at eliminating the inrush current that brought by residual voltage, a fast, reliable and easy implemented control strategy is proposed to restart a free-running induction machine. The cause of the inrush current is analyzed. An estimation method of the residual rotor flux is developed without any stator current information, since the power supply is cut off. Based on the estimated amplitude and electric angle of rotor flux, back-EMF is calculated. A novel application of the existing feedforward current controller is imployeed to compensate the residual voltage. Both the estimation method and the control strategy is verified with simulation and experimental results.