| US 7,557,583 B2 | ||
| System and method for monitoring an electrical power relay in a hybrid electric vehicle | ||
| Andrew M. Zettel, Ann Arbor, Mich. (US); Michael J. Miller, Macomb, Mich. (US); James C. Gibbs, Clinton Township, Mich. (US); and Mary A. Jeffers, Clarkston, Mich. (US) | ||
| Assigned to GM Global Technology Operations, Inc., Detroit, Mich. (US) | ||
| Filed on Nov. 21, 2005, as Appl. No. 11/285,523. | ||
| Prior Publication US 2007/0115604 A1, May 24, 2007 | ||
| Int. Cl. G01R 31/327 (2006.01) | ||
| U.S. Cl. 324—418 [324/421] | 15 Claims |
| 1. System for monitoring an electrical relay operable to conduct electrical power from a source to a load device in an operator
controlled vehicle, comprising:
an electrical relay including a pair of electrical contacts controllably opened and closed;
a resistive device, permanently electrically connected across the pair of electrical contacts such that when the pair of electrical
contacts is closed the resistive device is substantially shorted by the closed electrical contacts and when the pair of electrical
contacts is open the resistive device is in circuit between the open electrical contacts;
a controllable electrical load device electrically connected to an electrical power source through the resistive device when
the pair of electrical contacts is open and primarily through the pair of electrical contacts when the pair of electrical
contacts is closed and the resistive device is substantially shorted by the closed electrical contacts;
at least one sensing device measuring one of a) voltage across the resistive device and b) actual current supplied to the
controllable electrical load device; and,
a controller identifying a vehicle shutdown command from the operator,
commanding the controllable electrical load device to operate at a known current draw level,
commanding the relay to open the pair of electrical contacts, and
determining from the measured one of a) voltage across the resistive device and b) actual current supplied to the controllable
electrical load device, and a corresponding voltage threshold and current threshold, respectively, whether the pair of electrical
contacts has opened.
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