Fault diagnostic device and fault diagnosis method for an inverter

摘要

A control unit of an inverter for driving a three-phase motor receives a voltage of a connection point from a circuit in which the connection point connecting one end of each of three first resistors to a ground through a second resistor and the other end of each the first three resistors are connected to each phase. The control unit diagnoses whether the inverter has suffered an error based on the voltage of the connection point, the voltage being detected when a first switch provided on a positive bus is turned off, a second switch parallel to the first Switch is provided and in series with a third resistor is turned on, a third switch, which is provided in series with a fourth resistor between the power source and the connection point, is turned on and the switching elements according to a predetermined pattern on or off.