| 摘要 |
PURPOSE:To decrease excitation current and load current and to miniaturize an induction motor by amount corresponding to this, by a method wherein terminal voltage is increased even at control region other than constant torque region. CONSTITUTION:A control element 5 compares a detected value VM of the present rotational speed of an induction motor 3 with a target speed value VFS given from a command circuit. Output frequency of a DC/AC converter 2 is varied so that both values are coincident, and a control element 6 constituted by a read only memory generates a control signal of the output voltage value corresponding to output voltage frequency, thereby controlling the output voltage of the DC/AC converter 2. In this case, a control signal varying corresponding to variation in terminal voltage V is previously set to the control element 6. |
