METHOD FOR CONTROLLING THE STARTING OF AN AC INDUCTION MOTOR

摘要

A method is provided for controlling the starting of an AC induction motor (12) with a soft starter (14). The windings (20a-20c) are connected in a delta configuration and each winding has a corresponding thyristor switch (22a-22c) connected in series therewith such that each winding (20a-20c) and thyristor switch (22a-22c) combination is connected between two corresponding terminals (13a-13c) of the AC induction motor (12). Alpha control of the thyristor switches (22a-22c) is utilized to start the AC induction motor (12) and bring the AC induction motor (12) to near full operating speed. As the AC induction motor nears full operating speed, gamma control of the thyristor switches (22a-22c) is utilized to bring the AC induction motor (12) to full operating speed. With the AC induction motor (12) at full operating speed, bypass contactors (24a-24c), in parallel across corresponding thyristor switches (22a-22c), are closed and the AC induction motor (12) operates in a conventional manner.