To provide an inverter device having a detecting circuit constituted of inexpensive components, which can execute ground fault detection even during the operation of the inverter, letting alone detecting dead ground fault, and can detect over-current at the same time.
A positive side current detector 3 and a negative side current detector 4 are inserted between a smoothing capacitor 5 and the input terminal of inverter 6, the detected value of each current detector 3, 4 and a reference value are compared by a positive side differential comparator 10 and a negative side differential comparator respectively, a signal output 12 obtained by level-shifting the output of the positive side differential comparators 10, 11 from the positive side potential to the negative side potential digital signal and the output of the negative side differential comparator, are both used as an over-current detecting signal 32, and both outputs are input into a counter 13 to use the count output 20 of the counter 13 as a ground fault detecting signal.
HIGUCHI MASAHITO
Hironori Honda
Toshimitsu Ichikawa
Takeshi Takamatsu