Patent ID: 7095244
Filing Date: 2006-08-22
Classification: B62D,H01H,H02H

Abstract:
1. A method for determining operational states of first and second electrical contacts in a motor, the motor having first, second, and third phase windings, the first phase winding being electrically coupled between first and second nodes, the second phase winding being electrically coupled between a third node and the second node, the third phase winding being electrically coupled between a fourth node and the second node, the first electrical contact being electrically coupled between the first node and the third node, the second electrical contact being electrically coupled between the third node and the fourth node, the method comprising: applying a first voltage signal to the first phase winding at a first time; measuring a second voltage signal at the third node coupled to the second phase winding; measuring a third voltage signal at the fourth node coupled to the third phase winding; and determining first and second operational states of the first and second electrical contacts, respectively, based on first and second amplitudes of the second and third voltage signals, respectively, at a second time, the second time being a predetermined time period after the first time.