DC POWER SUPPLY UNIT, MOTOR DRIVE DEVICE, AIR CONDITIONER, REFRIGERATOR, AND HEAT PUMP HOT-WATER SUPPLY APPARATUS

摘要

PROBLEM TO BE SOLVED: To solve the following problem: a conventional DC power supply unit cannot perform stable power conversion with small conversion loss even when a load fluctuates over a wide range from a low load to a high load.SOLUTION: The present invention is configured so that short-circuit means 11 is opened to pass an electric current through a low-frequency reactor under a low load state and so that bidirectional switching means 16 is operated to control so that an end-to-end voltage of smoothing means 6 is higher than a voltage peak value of a power voltage and to short short-circuit means 11, thus passing an electric current through a high-frequency reactor.