| 摘要 |
PURPOSE:To always highly efficiently operate an induction motor at a prescribed frequency with a preset slip in accordance to a load by modulating a pulse- width-modulated signal by using a parameter compensated based on the function of the voltage supplied to the motor. CONSTITUTION:A power controller 26 for an induction motor is provided with a pulse width modulating circuit 32 which generates a pulse-width-modulated signal 32a and operates an induction motor 12 at a variable speed by driving an inverter section 18 in response to the signal 32a and converting DC power into AC power of a variable voltage and variable frequency. The controller 26 is provided with a modulating means 35 which changes the voltage supplied to the motor 12 from the lower limit value to the upper limit value along the load of the motor on a plurality of curve patterns at every frequency by modulating the pulse-width-modulated signal of the circuit 32 by using a modulating parameter compensated based on the function of the output of a frequency commander 24 and the voltage supplied to the motor 12. |
