Alternating current-direct current converting apparatus and apparatus for driving electric machinery

摘要

Provided is an alternating-current direct-current converter capable of controlling a harmonic current and improving a power factor at reduced costs. The alternating-current direct-current converter includes two capacitors connected in series between output terminals of a rectifier (2); a first switch (3) connected between one input terminal of the rectifier (2) and a connection point of the capacitors; a second switch (4) connected between the other input terminal of the rectifier (2) and the connection point of the capacitors; a voltage detector (21) which detects terminal voltages of the capacitors; a current detector (22) which detects a current input from the alternating current power supply (1); and a control means (20) which drives and controls the first switch (3) and the second switch (4), in which the control means (20) drives and controls the first switch (3) and the second switch (4) such that the terminal voltages of the capacitors are fixed and a power supply power factor is improved using an active power component and a reactive power component obtained by conversion of detection results of the current detector (22) and detection results of voltage detector (21).