PURPOSE:To obtain a fault diagnostic device, which specifies a fault semiconductor element while using a multiplexed inverter as an object and is miniaturized and in which the number of wirings among related equipments is decreased, for an inverter. CONSTITUTION:Semiconductor elements Q1 to Q4 of each unit are supplied with gate driving power through gate driver circuits 31 to 34 while employing an inverter device consisting of the parallel multiple constitution of inverter-units 11 to 13 as an object. Gate driving powers 21 to 23 outputting supply capability value signals and a constant current source 8 charging the smoothing capacitors Cf of each unit by DC constant currents and emitting the signal of reaching to a fixed value of the charging voltage of each capacitor when the charging voltage reaches the fixed value are mounted. A control circuit 6 commanding normal inverter operation and on-off controlling the elements Q1 to Q4 of each unit in accordance with specified order at the time of and a fault decision display circuit 7 deciding each suitability of each gate driving power value and a charging duration and specifying the semiconductor elements of each unit under a fault state are installed.
展开▼
