| 摘要 |
PROBLEM TO BE SOLVED: To continue the operation even in a system with large load inertia by realizing the PI control of the value multiplied by two kinds of deceleration rates to control the deceleration time, and stopping the deceleration if the voltage reaches the value before detecting the power failure, or the DC intermediate voltage is boosted during the deceleration. SOLUTION: A PI controller 16 operates the deceleration rate 1 by the target value of the DC intermediate voltage and the detected value so that an AC motor is smoothly decelerated in a short transmission interruption, and operates the deceleration rate 2 by the change of rate of the DC intermediate voltage, and realizes the PI control by the value multiplied by these two deceleration rates. The rotational speed of an AC motor is smoothly reduced. When a voltage boosting detection circuit 17 detects the boosting of the DC intermediate voltage, or the boosting of the voltage over the voltage before detecting the power failure is detected by a voltage detection circuit 18, a deceleration stopping means 19 is operated to stop the deceleration. The dropping/boosting ratio of the DC intermediate voltage is reduced to continue the operation irrespective of the size of the load inertia. |
