| 摘要 |
PURPOSE:To prevent a flux control means from falling into unstable condition by the sudden change of a torque polarity, by selecting an acceleration operating means, a deceleration operating means and a constant speed means in accordance with a signal from a torque polarity discriminating means. CONSTITUTION:The title circuit is provided with an acceleration operating means 22, increasing a frequency commanding value with a predetermined changing speed, a deceleration operating means 24, reducing the frequency commanding value with a predetermined changing speed, and a constant speed means 23, which does not change the frequency commanding value. Either one of these means 22, 23, 24 is selected by a switching control means 26 in accordance with a signal from a torque polarity discriminating means 25. When the polarity of torque is converted suddenly, a constant speed operation is effected by a constant speed means 23 for a predetermined period of time, thereafter, the operation is effected with the torque polarity just in accordance with the command. |
