| 摘要 |
PURPOSE: To make a ratio of an output frequency and an output voltage changeable by changing a frequency according to a load torque after a plurality of selected frequencies and voltages corresponding to each other are set and stored. CONSTITUTION: A frequency memory means 1 and a voltage memory means 2 store N-kinds of frequencies and voltages, and these data, for an example a first frequency and a first voltage, are sequentially set in a pair to select desirably a ratio of the output voltage to the corresponding output frequency. When a frequency selecting command Fin is entered in a frequency selecting means 3, a pair of frequency and voltage are read out from the frequency memory means 1 and the voltage memory means 2 and fed to a pulse width modulation signal circuit 4. Then, the ratio of the output voltage to the output frequency is changed only by changing the frequency on the basis of a frequency command, and at the same time the magnetic flux at the void in the induction motor 9 can be changed. |
