| 摘要 |
PURPOSE:To start an inverter regardlessly of the rotating condition of an AC motor, by adding the output of a speed command compensation circuit controlled by the outputs of an input current detector and a rectifier voltage detector, to the output of a ramp signal generation circuit. CONSTITUTION:The output of a detector 17 for a DC voltage VD and the output of a current detector 9 are applied to a speed command compensation circuit 13. The polarity of the DC voltage VD is discriminated. When the DC voltage is negative, namely, a regenerative state is, an output proportional to a current is generated if the current is higher than a set level IO which is selected to be lower than an allowable limit of an inverter. The output of the speed command compensation circuit 13 is added to that of a ramp signal generation circuit 7. As a result, a voltage V and a frequency f rise quickly when the current has increased over the set level IO in the regenerative state. Thus, the regenerative state is eliminated, the current decreases and smooth starting is enabled. |
