| 摘要 |
<p>PURPOSE:To enable an induction motor to be efficiently operation-controlled with a low magnetic sound, by making the ratio of output voltage to the output frequency of a power converter at the time of constant speed operation control, less than the ratio at the time of normal operation control. CONSTITUTION:When a master controller 6 is made at the position of a constant speed notch 6b, then by the signal of a constant speed command wire 19, change- over switches 9 and 10 are switched. In the meantime, by a desired speed setting unit 20, the vehicle speed signal fr at the time is latched, and the signal is set to be following speed command signal fp. Besides, the input of constant speed command signal to a V/f converter 16 for controlling the ratio(V/f) of frequency f to voltage V is also provided, and is switched so that the conversion ratio of the V/f of the V/f converter 16 may be a low specified value. As a result, an induction motor can be efficiently operated, and magnetic noise can be lowered.</p> |
