| 摘要 |
PROBLEM TO BE SOLVED: To obtain a method in which the torque of an AC motor is controlled in a system containing a controllable variable-frequency AC power source coupled to the AC motor used to drive a variable load such as a pump. SOLUTION: At a step, AC power is applied to an AC motor from a variable- frequency AC power source, and the frequency of the AC power is raised at a comparatively fast rate from nearly zero Hz. At a step, the AC power is applied, and the frequency is raised. At the steps, a motor current is monitored, and the motor current is compared with a prescribed magnitude. A step at which, when the motor current exceeds the prescribed magnitude, the frequency of the AC power is lowered until the motor current becomes smaller than the prescribed magnitude, at which, after the motor current has become smaller than the prescribed amplitude, the AC power is applied and at which the frequency is raised, monitored and compared are repeated is contained. The comparatively fast rate is selected in such a way that the motor is accelerated at a nearly constant torque. |
