| 摘要 |
PURPOSE:To improve the accuracy and the transient response of an inverter output voltage and reduce a distorsion rate with respect to the higher harmonic of a load, by outputting the current commanding value of a transducer by an AC sine wave output voltage. CONSTITUTION:A capacitor current commanding unit 12 provides an adder 13 with the d-shaft commanding value and the q-shaft commanding value of a current to be conducted through a capacitor 3. Next, a voltage controlling unit 11 receives a difference between the commanding value of a voltage commanding unit 9 and a feedback signal from a 3-phase/2-phase converting unit 6 and provides the adder 13 with a control signal to make the difference zero. Subsequently, a forecaster 10 receives the values of load current, which are converted into d-q shafts, and forecasts the load current of preceeding one sample from past and present load current values by employing a two-dimensional forecasting formula and the like and provides the adder 13 with the forecasted load current. A limiter 14 products the output of the adder 13 by a limiting factor and provides it as a current command whereby an output overcurrent is converted into a sine wave voltage waveform by the restriction of an inverter itself. |
