METHOD FOR CONTROLLING THE STARTING OF AN AC INDUCTION MOTOR WITH CLOSED LOOP CURRENT CONTROL

摘要

A method is provided for controlling a three-phase, AC induction motor. Each phase of the AC induction motor is connected to an AC input source by a thyristor switch and a bypass contactor connected in parallel in order to provide voltage and current to the AC induction motor. The method includes the steps of sequentially firing pairs of thyristor switches at a predetermined initial gamma firing angle. A new gamma firing angle is calculated which is dependant upon the initial gamma firing angle. Thereafter, pairs of thyristor switches are fired at the new gamma firing angle. The new gamma firing angle is provided as the initial gamma firing angle and a new gamma firing angle is calculated. The process is repeated until the AC induction motor reaches its full operating speed.