| US 7,612,576 B1 | ||
| Method for detecting an inverter hardware failure in an electric power train | ||
| Marcus Heller, Farmington Hills, Mich. (US); and Jody Nelson, West Bloomfield, Mich. (US) | ||
| Assigned to Daimler AG, Stuttgart (Germany) | ||
| Filed on Aug. 19, 2008, as Appl. No. 12/229,071. | ||
| Int. Cl. G01R 31/34 (2006.01); G01R 31/00 (2006.01) | ||
| U.S. Cl. 324—772 [324/143; 318/490; 318/638] | 11 Claims |
| 1. 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.
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