JPS6469281A - Inverter controller - Google Patents

Abstract

PURPOSE:To prevent an overcurrent from generating by rapidly decelerate an output frequency command signal on the basis of a set output frequency, an output current, etc., at the time of restricting a motor shaft to quickly decelerate it. CONSTITUTION:An inverter is composed of a power reactor 2 for rectifying an AC power source 1, a smoothing capacitor 3, and a power inverter 4, and an induction motor 5 is operated by its AC output. A controller is composed of a frequency setter 7, an acceleration/deceleration controller 8, and a PWM controller 10. In this case, an output current detector 21, a comparison reference setter 22, a reference comparator 23, first, second comparators 24, 25, an AND gate 26, a quick deceleration controller 27, and an output frequency command signal selector 28 are provided. Thus, when the motor shaft is restricted, its state is detected by the comparator 25 under the condition that the output current is a predetermined value or more. When the AND condition of the comparators 24, 25 is satisfied, the controller 27 rapidly reduced the output frequency command signal.