| 摘要 |
PURPOSE:To enable the power unit to stably supply a prescribed voltage to a load without adding any special device to the unit by making a self-excited converter operate as a reactive power adjuster in a by-pass feeding mode which is set when an inverter becomes defective while commercial power supply is normal. CONSTITUTION:When an inverter 5 is sound, the AC voltage of commercial power supply 1 is fed to a load 8 through an input transformer 2, self-excited converter 3, etc. In addition, a switch 23 is closed and the voltage of the power supply 1 is selected as a reference voltage, and then, the input voltage of the converter 3 is controlled so that the voltage can become equal to the voltage of the power supply 1. When the inverter 5 becomes defective, a change-over switch 7 is set to a by-pass circuit 6 side by means of the output of a fault detector 21 and, at the same time, a switch 22 is opened. As a result, the phase adjustment of a PLL 16 is shifted to the vicinity of zero. In addition, a switch 24 is closed and the converter 3 is operated as a reactive power adjuster by using a prescribed reference AC voltage as a reference voltage. |
