| 摘要 |
PURPOSE:To obtain a necessary torque and to maximize the efficiency of an induction machine by providing detecting means for detecting effective value of a primary current of an induction motor, monitoring an increase or a decrease in the current when the output voltage of an inverter is increased or decreased at a predetermined value, obtaining the output voltage so that the current becomes minimum and controlling it. CONSTITUTION:A set frequency f** applied from a frequency setter 1 becomes a frequency command f* through an integrator 2, and is input to a PWM pulse generator 3. The set value f** is also applied to a functional generator 4 which calculates a set voltage lambda** to the command f** to correspond to a V/F pattern and outputs it. An automatic torque boost calculator 5 searches an optimum voltage command lambda* based on the set voltage lambda** and the amplitude I1 of the primary current detected by a current detector 6. The generator 4 inputs the command f* and the command lambda*, calculates a PWM pulse width of a predetermined carrier frequency, and it is supplied as a PWM pulse signal to a switching element of a voltage type PWM inverter 7. |
