DISTURBANCE OBSERVER FOR TWO-INERTIA SYSTEM AND SPEED CONTROL DEVICE EMPLOYING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a disturbance observer for a two-inertia system in which a state quantity can be estimated accurately even when there is load disturbance, and a speed control device for the two-inertia system employing the same.SOLUTION: A disturbance observer 8 for applying estimated disturbance torque to a state observer 7 in order to estimate a state quantity of a control object 1 of a two-inertia system is configured to determine the estimated disturbance torque by multiplying motor torque by a first transfer function 81, subtracting from a result of the multiplication a value resulting from multiplying a rotating speed of a motor by a second transfer function 82, and filtering a result of the subtraction by a filter 83 of third order or more. The first and second transfer functions 81 and 82 are determined by calculating the disturbance torque backwards from a transfer function of the two-inertia system for determining the motor speed.