| 摘要 |
PURPOSE:To avoid an overexcitation state by boost-compensating only at an acceleration time to smoothly start and operate in a normal state at low frequency constant speed rotation time. CONSTITUTION:A voltage booster 17 has a calculator amplifier 18 which inputs a frequency set voltage Va output from a speed setter 6 and an acceleration/ deceleration slope signal Vb output from accelerator/decelerator 7 and compares both, a boost amount regulating variable resistor 15, and a diode 16. The booster 17 operates to apply the boost voltage signal through the resistor 15 and the diode 16 to the input of the second comparator 11 only in case of the voltage Vbnot equal to Va. |
