Abstract: An acoustic signal in an elevator door system is provided if a door close signal is present and a door has not closed within a determined time. A switching frequency of a pulse width modulation signal is reduced such that a motor is caused to provide the acoustic signal.

Abstract: An automatic sliding door operator includes a top door operator and a bottom door operator, each operator having a motor driven sprocket driving a tooth belt to which the sliding doors are attached, the motors being separately driven in a position-synchronized fashion in response to related encoders connected with each motor to provide positional information.

Abstract: An apparatus for controlling an elevator door includes a three phase AC motor that receives control signals from a controller. The signals are issued at control points along a speed versus distance profile map that represents the control points as a percentage of the total distance to be travelled by the elevator. The total distance of door travel in one direction is measured be counting the number of pulses generated by an incremental encoder during a training run wherein the door is moved between its extreme positions at a constant speed. The number of pulses counted is then normalized to represent 100% of the distance traveled. During operation, the pulses are counted whenever the elevator door is in motion and control signals are issued based upon the number of pulses counted.

Abstract: The DC link current from one leg of a DC link of an inverter is provided to a primary winding of an AC current transformer, and a voltage across the secondary winding of the current transformer is integrated for providing an envelope indicative of the DC link current.