Patent ID: 7612576

Claim:
A method for detecting an inverter hardware failure in a power train having a positive and a negative terminal, a high voltage battery, high voltage cables, at least one electric machine and at least two inverter legs with two power electronic switches respectively for pulse-width-modulating a DC voltage from the high voltage battery for energizing the at least one electric machine, the power train being connected to the high voltage battery via a link comprising a bulk capacitance and a Y-capacitance, both being connected to the positive terminal and to the negative terminal of the high voltage battery, and a center tapping of the Y-capacitance additionally being connected to a metallic housing electrically isolated from the battery, and including at least one mid-pack voltage sensor for detecting isolation faults, said method comprising the steps of: commanding all power electronic switches open; closing and opening one of the power electronic switches of one of the legs at a certain time at a given duty cycle and a given frequency; measuring a mid-pack voltage using the mid-pack voltage sensor; identifying the switch as functional if, with the switch closed, a common mode voltage is detected by the mid-pack voltage sensor or, otherwise, identifying the closed switch as non-functional.