UNINTERRUPTIBLE POWER UNIT

• Main Authors: UMETSU HIDEYASU, SHIMADA KEIZO, KUNISADA HIDEAKI
• Format: Patent
• Language: English
• Published: 02.07.1999
• Edition: 6
• Subjects: CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION; SYSTEMS FOR STORING ELECTRIC ENERGY

PROBLEM TO BE SOLVED: To provide an uninterruptible power unit which is able to suitably suppress the deterioration of the efficiency and input power factor of the overall device. SOLUTION: An uninterruptible power unit is provided with a first converter 4, which is connected between a DC power storage device 5 and a load device 3 and is able to make power conversion in both the forward and reverse directions, a switch 2 which turns on/off an AC power source 1, and a second converter 6 the switch of which is connected in series with the power source 1 together with its AC output side and can make reverse conversion. When the power source 1 is normal, the first converter 4 is controlled so at to supply electric power to the second converter 6 and the storage device 5, and at the same time, reactive power containing the harmonic current required by the load device 3 through the control of the second converter 6 so that the sum of the AC output voltage of the converter 6 and the AC power supply voltage becomes constant. When the power unit 1 becomes lower than an allowable voltage, the first converter 4 is controlled so that the AC voltage impressed upon the load device 3 becomes constant by opening the switch 2.