| 摘要 |
PURPOSE:To accurately detect the AC current of an inverter by detecting the DC current of the inverter by a detector which can detect normal or reverse current and calculating with a signal proportional to the output frequency and a signal corresponding to a power factor. CONSTITUTION:A voltage type inverter is formed of a power converter 1, a capacitor 2 and a power inverter 3, thereby driving an induction motor 5. A detector 9 which can detect the normal and reverse currents is provided in a DC line, the voltage signal is divided by a divider 11 by a signal obtained by multiplying the signal of a frequency controller 9 which applies a trigger signal responsive to the output frequency to the power inverter 3 by a signal of a function generator 14 which generates a signal corresponding to the power factor as a function of the primary current of a motor 5, a coefficient K is multiplied, and an AC current is calculated. Accordingly, it can discriminate either the drive current or the regenerative current, and the AC current of the inverter can be accurately detected over wide range irrespective of the magnitude of the primary current. |
