| 摘要 |
PURPOSE:To smoothly control the accelerating/decelerating operation in a wide speed range from low to high speeds by controlling the voltage so that V/f becomes constant in a high speed range and so that a magnetic flux becomes constant in a low speed range. CONSTITUTION:A priority circuit 13 preferentially outputs a frequency target value signal F* in a high frequency range, and a priority circuit 23 preferentially produces the output signal V0 of a voltage detector 21. In other words, the terminal voltage VM of an induction motor 6 is controlled to be proportional to the frequency so that V/F becomes constant in a range operating by high frequency. The circuit 13 outputs the magnetic flux target value signal phi*as it is in a low frequency range, and the circuit 23 preferentialy produces a magnetic flux signal phi output from a magnetic flux detector 22 to a comparator 14. Thus, an inverter 8 is controlled so that the magnetic flux of the motor 6 maintains the target value phi* irrespective of the output frequency of the inverter. |
