Abstract: A transportation system such as an elevator utilizes a static power converter to directly energize a D.C. drive motor and another static power converter to directly energize a friction type braking element and automatically selects a mode of operation best suited for safe operation from a plurality of modes including a normal operation, a reduced speed operation, an emergency landing operation and an emergency operation in response to certain sensed malfunctions within the system including a decrease in the source voltage to a predetermined magnitude, an increase in the armature current of the D.C. motor to a predetermined magnitude, a decrease in the field current of the D.C.

Abstract: One layer of three heat sinks for conducting alternating current and a second layer of two heat sinks for conducting direct current sandwich twelve controlled rectifiers which are electrically arranged to provide a pair of gated rectifier bridge networks for changing from a current of one frequency to a current of another frequency. Six rod-like bolts are removably secured within threaded openings of certain heat sinks and pass through openings within other heat sinks and assist together with locking nuts in compressing the sandwiched assembly. Three of the bolts are electrically insulated from the direct current heat sinks for supplying alternating current to the rectifying devices through the alternating current heat sinks while two of the bolts are electrically insulated from the alternating current heat sinks for conducting direct current to the rectifying devices through the direct current heat sinks.

Abstract: A solid state static converter receives a three-phase A.C. input and directly supplies direct current to a D.C. motor operating a traction sheave to control the movement of an elevator car in response to an error signal derived by the selective summation of a speed signal from a tachometer and a pair of vehicle speed command signals. One command signal is a function of the commanded velocity versus time and operatively controls the system during acceleration, constant velocity and a portion of deceleration. The other command signal is a function of the commanded velocity versus time as modified by the sensed position of the car and solely operatively controls the system during a portion of deceleration to stop the vehicle at a selected landing.

Abstract: A solid state static converter is connected to receive a three-phase A.C. input and directly supply a direct current output to a D.C. motor which operates a traction sheave to control the movement of an elevator car. The magnitude and direction of the direct current output from the static converter is controlled by an error signal derived by the summation of a speed signal obtained from a tachometer coupled to the motor drive shaft and a vehicle speed command signal provided by a pattern generator and having maximum velocity, acceleration and rate of change of acceleration limitations for safe and smooth control of the elevator car and for accurate stopping at landings.

Abstract: A first solid-state static converter receives a threephase A.C. input and directly supplies direct current to a D.C. motor armature circuit to operate a traction sheave and control the movement of an elevator car in response to an error signal derived by the summation of a speed signal from a tachometer and a vehicle speed command signal while a second solid-state static converter receives a three-phase A.C. input and directly supplies direct current to a field circuit of the D.C. motor in response to the operation of a field gating control circuit.