UNINTERRUPTIBLE POWER SUPPLY

摘要

An uninterruptible power supply for preventing an instantaneous stop when the operation is switched to an inverter operation by separating the voltage input side from the system if the input voltage lowers. The input voltage is supplied to the load through an AC switch (5) composed of thyristors connected in inverse-parallel to allow the thyristor through which a current of the same polarity as the input voltage to conduct. A parallel converter (12) connected to a feed line (LN) is allowed to carry out rectification operation to charge a battery (14). A series inverter (18) is allowed to carry out inverter operation using the battery (14) as an energy source. The output of the series inverter (18) is supplied in series to the feed line (LN) though a series transformer (19) to correct the output voltage applied to the load. If the input voltage lowers, the thyristor controlled to conduct is automatically cut off when a reverse bias is applied. When the operation of the parallel converter (12) is switched to an inverter operation, the switch (5) is in an off state. Therefore, any instantaneous stop of power supply to the load caused when a current flows through the AC switch (5) and a short-circuit part is prevented.