CONTROLLING METHOD FOR SPEED OF INDUCTION MOTOR

摘要

PURPOSE:To control an induction motor as predetermined with constant power factor by suitably controlling the exciting current in response to the load. CONSTITUTION:Secondary current I2 is divided by exciting currents I0 by a divider 21. A comparator 22 compares the set command value of I2/I0 with the calculated value from the divider 21, the deviation between the set command value and the calculated value as the output from the comparator 22 is amplified by an exciting current controlling amplifier 23 and produces a predetermined exciting current command value. This value is applied to a switch 13 which obtains the secondary current I2 and a voltage control system for the power inverter. In this manner, the power factor is controlled constantly to control the relative ratio between the secondary current I2 and the exciting current I0 as instructed.