Strategy for Restarting the Free-Running Induction Motor Driven by a High-Voltage Inverter Based on V/F Fuzzy Control

The adoption of the conventional V/f control strategy for restarting a free-running induction motor driven by a high-voltage inverter tends to cause an impact current on the stator side. This paper proposes a fuzzy-logic control method. The method makes the output frequency follow the motor speed without knowledge of motor parameters or speed feedback when the motor is in a field-weakening state. Then the motor can be accelerated to the rated speed after the stator flux is increased to the rated value, thereby avoiding a large stator current when restarting the motor. Besides, the proposed method is of good robustness to the load coefficient when the load coefficient deviates from the rated value. The simulations verify that the theoretical analysis and the proposed method are correct and effective.