Abstract: When main power to an elevator system 10 is lost, an automatic rescue operation is performed using power from a backup power source 46. A rescue run for an elevator stopped between floors is initiated by lifting a brake 28 and allowing the elevator car 12 to move by gravity. If the car 12 moves as a result of a weight imbalance between the car 12 and a counterweight 14, operation of the hoist motor 24 is synchronized with sensed movement of the car 12 to generate electricity. If weight is balanced so that the car 12 does not move, backup power is supplied to the hoist motor 24 to apply a motor torque to drive the car 12 in a selected direction during the rescue run.

Abstract: When main power to an elevator system 10 is lost, an automatic rescue operation is performed using power from a backup power source 46. A rescue run for an elevator stopped between floors is initiated by lifting a brake 28 and allowing the elevator car 12 to move by gravity. If the car 12 moves as a result of a weight imbalance between the car 12 and a counterweight 14, operation of the hoist motor 24 is synchronized with sensed movement of the car 12 to generate electricity. If weight is balanced so that the car 12 does not move, backup power is supplied to the hoist motor 24 to apply a motor torque to drive the car 12 in a selected direction during the rescue run.