METHOD FOR DETECTING SPEED OF MOTOR BY GENERATING FAULT SIGNALS UPON OCCURRENCE OF TROUBLE IN ENCODER

摘要

PURPOSE: A method is provided to prevent damages of a motor caused due to an excessive current by generating fault signals upon occurrence of trouble in an encoder. CONSTITUTION: A method comprises a first step(S61 to S72) of maintaining the speed of a motor at zero or at the previous speed in accordance with the change of position of the motor during a speed detection cycle; and a second step(S73 to S79) of calculating an encoder pulse input time by comparing the estimated speed and speed command in cases where an inverter is in operation, checking whether an encoder pulse is input or not within the calculated encoder pulse input time, and outputting a fault signal in cases where the period of non-pulse is longer than the speed command.