| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an overcurrent from being passed through switching elements or reflux diodes in ground fault detection. <P>SOLUTION: The inverter device includes: a converter unit 14 that rectifies an alternating current inputted from an alternating-current power source 1; a smoothing unit 9 that is charged with the rectified output of the converter unit 14 and outputs smoothed voltage obtained by smoothing the rectified output; an inverter unit 15 that has the switching elements and the reflux diodes connected in parallel with the switching elements and carries out PWM control to supply an alternating current from its output to a load; current detection units 5a to 5c that detect the value of a current flowing to the output of the inverter unit 15; a duty setting unit that sets the on/off time of the switching elements; a gate control unit 10 that turns on/off the switching elements based on a duty; and a ground fault resistance estimation unit 21 that estimates a ground fault resistance on the basis of the duty and a current value. With respect to the duty, an on-time is set so that, when the output of the inverter unit 15 is connected to the ground, an overcurrent is not passed through the switching elements. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
