| 摘要 |
PURPOSE:To suppress voltage fluctuation when a power source is switched by controlling an inverter such that the effective component at the commercial source side will be zero when the inverter is connected to a load which is connected to a commercial power source circuit. CONSTITUTION:Under parallel operation of a commercial power source 1 and an inverter 2, output from an effective current detecting circuit 17 at the commercial side is fed through a first error amplifier 26 to a phase difference signal forming circuit 28, where a signal for correcting the phase difference is formed and phase correction is made based thereon. Phase control is made so that the effective current will be zero, and thereby the effective current at the side of the commercial power source 1 will be zero when the phase control operation is stabilized and the load is fully born by the inverter 2. Consequently, the commercial power source 1 has substantially no relation with the load 3 and power is fed only through the inverter 2 to the load 3 by turning a first source switch S1 OFF. |
