| 摘要 |
PURPOSE: To control the generation of higher harmonics and unbalance by zero-phase current element of a multiphase circuit having a zero-phase circuit by detecting zero-phase element from a detected current of a 3-phase load current and distributing such zero-phase element for addition to a 3-phase compensating current instruction value. CONSTITUTION: A zero-phase current compensating circuit 20 adds each load current transforming signal of each phase R, S, T with an adding circuit 21 to obtain a zero-phase current element, obtains a zero-phase current compensating amount distributed to each phase by multiplying the coefficient 1/3 to the zero-phase current element in a coefficient arithmetic circuit 22, adds this zero- phase current compensating amount to each phase compensating current command value from a phase converter 12' in the addition circuits 23R, 23S, 23T to define each phase compensating current command value as an output current command value of the current control circuit 24 of the current generating source. Therefore, the zero-phase current in the power source side is set to zero by generating the particular zero-phase current to the 3-phase 4-wire circuit as a compensating current from an active filter. Thereby, the influence of higher harmonics component and unbalance included therein can be removed. |
