VARIABLE FREQUENCY POWER UNIT CONTROLLING SYSTEM

摘要

A variable frequency power unit controlling system for controlling a variable frequency power unit to supply an electric current of a frequency corresponding to a desired revolving rate of an electric motor. A control signal designating the revolving rate of the electric motor is integrated by an integrating circuit and the output frequency of the variable frequency power unit is held at a predetermined value regardless of the control signal, when the change rate of the output signal of the integrating circuit deviates from a predetermined range of change rate.