| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect ground fault of a multiphase load without need of additional hardware for detecting ground fault. <P>SOLUTION: Before operation start of an inverter, only a switch KO is conducted with switches K11, K12 opened in a switching group SW. At least one of switches Q21, Q22, Q23 is conducted. If a ground fault JO occurs, a current flows from an R-phase power supply through conducting one or ones of the switches Q21, Q22, Q23, a diode D14, and the switch KO, so that the current is detected as a current IM. If the ground fault JO does not occur, naturally, the current IM will not flow. That is, it is detected that whether or not the ground fault occurs in a motor P based on the presence of the current IM. A current detector CT is conventionally provided for detecting whether or not an overcurrent flows during operation of the inverter INV, thus additional hardware is not required to be provided for detecting a ground fault current. <P>COPYRIGHT: (C)2007,JPO&INPIT |
