| 摘要 |
PURPOSE:To eliminate a basic wave component of error current and to increase a current accuracy by superimposing a proportional signal to correspond to the voltage of an a.c. power system for correcting a current deviation and by using the corrected current deviation in the PWM control. CONSTITUTION:Using the voltage of a voltage-type inverter 1 at a connection between the converter and an a.c. power system which is detected by a transformer 8, the voltage (VAC) of the a.c. power system is calculated. The calculated voltage is superimposed by an adding circuit 7 on a current deviation between an output current detected value I and an output current command value I'. At that time, the value K3 of the voltage VAC K3 (K3 is a coefficient) to be applied to the adding circuit 7 is so set as to meet 1-K2.K3=O (K2 is a conversion coefficient of the inverter) and the current deviation is corrected according to a proportional signal which is proportional to the voltage of the a.c. power system and then PWM control is conducted. As a result, a component which is included in the current deviation and which is a current deviation generating factor is eliminated and thereby a basic wave component of the error current can be directly eliminated. Consequently, a current accuracy in the current follow-up control can be remarkably increased. |
