VECTOR CONTROL DEVICE FOR INDUCTION MOTOR

摘要

PROBLEM TO BE SOLVED: To provide a vector control device which prevents the appearance of overcurrent when a motor constant in the control deviates from an actual motor constant of an induction motor. SOLUTION: A vector control device is provided with a current control system which makes a proportional-plus-integral operation of a difference between a torque current command I1b * of an induction motor and a detected value I1b and of a difference between an exciting current command I1a and a detected value I1a and limiters 6e, 6f which limit a torque shaft voltage V1b and an exciting shaft voltage V1a respectively. This device is also provided with overcurrent suppression means 14-16 which reduce the torque current command I1b * by the value proportional to the difference between the exciting current command I1a * and the detected value I1a when the difference comes near an overcurrent level of the induction motor. Also provided are overcurrent suppression means 17-19 which make the proportional-plus-integral controlled output of torque current zero and locks the limiter outputs of the exciting shaft voltage at prior values and limit the torque current command I1b * to zero when the difference between the torque current command I1b * and the detected value I1b comes near the overcurrent level of the induction motor.