| 摘要 |
PROBLEM TO BE SOLVED: To suppress DC offset produced in a single-phase or 3-phase AC system, enable the employment of an economical ripple detecting means, reduce the cost and minimize the influences of temperature change and change with time to improve reliability. SOLUTION: A power converter has an AC unit, a DC unit, a switching unit 1 connected between the AC unit and the DC unit and converts power by its switching operation and a control unit 6 which controls the switching unit 1. A ripple detecting means which detects a ripple component appearing on the DC side is provided in the DC unit. If a DC component is contained in the output current of the AC unit, a ripple component whose frequency is the same as that of the AC frequency of the AC unit output current is superposed on the output current of the DC unit. As the ripple detecting means is provided in the DC unit, the ripple component contained in the DC unit output current is detected and, in order to control the DC component contained in the current of the AC unit, the switching unit 1 is controlled by control signals including DC component compensation signals to compensate DC offset. |
