OPERATION OF UNINTERRUPTIVE POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To lessen noise of an uninterruptive power supply at the time when a power inverter is stopped and only a power rectifier is operated or at the time of light-load operation. SOLUTION: At the time of the stoppage of a power inverter 3 or at the time of light-load operation, an UPS control circuit 6 detects such an operating condition and then sends a signal for switching a carrier frequency of a power rectifier 2 to an analog switch and thereby the uninterruptive power supply device is operated with a different carrier frequency of the power rectifier 2. The carrier frequency of the power rectifier 2 at the time of the stoppage of the power inverter 3 and at the time of light-load operation is set higher than that at the rated operation. By this method, noise from an AC reactor, etc., can be lessened and noise of the uninterruptive power supply device can be lessened.