| 摘要 |
PROBLEM TO BE SOLVED: To detect the interruption of power supply in an uninterruptible power supply unit simply and at a low cost and, moreover, at a high speed. SOLUTION: In contrast to a usual unit wherein two kinds of integrators, i.e., an integrator conducting an integrating operation at phases of 0-180 and 180-360 degrees of a supply voltage and an integrator conducting the integrating operation at phases 90-270 and 270-90 degrees, are provided and comparators and memories (F/F) are provided in two circuits, the comparator (CP) and the memory (F/F) are provided in one circuit respectively and high-speed detection of interruption of power supply in a 1/4 cycle is enabled by a construction wherein a signal is outputted from a synchronous circuit 2A at each of phase points of 0, 90, 180 and 270 degrees of the supply voltage and the integrator 4 is reset and made to conduct the integrating operation by this output. |
