| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an overload detector which certainly detects an overload state of a rectification circuit irrespective of presence/absence of a DC reactor. <P>SOLUTION: In a DC power supply device which includes: a rectification circuit 2 which rectifies three-phase AC power supply voltage; and a main circuit capacitor 3 connected to the DC output side of the rectification circuit 2, and supplies the both end voltage of the main circuit capacitor 3 to a load 4, it includes: a current detector 19 which detects output current of the rectification circuit 2; a minimum value arithmetic unit 5 for calculating a square average value of the output current of a section to be sectioned by at least three minimum points in which the output current becomes the minimum value; an operation timing generator 6; a square average arithmetic unit 7; and an overload detector 9 which determines that the rectification circuit 2 is at the overload state when the square average value exceeds a preset overload detection level. <P>COPYRIGHT: (C)2012,JPO&INPIT |
