A speed control apparatus for an elevator wherein a current command signal for controlling the firing angle of dual thyristor converters is supplied through a filter circuit. On switching from one converter to the other pursuant to reversing the elevator direction, the filter circuit is reset to bring the current command signal momentarily to zero, after which it rises smoothly in a positive or negative direction together with the elevator motor armature current.

A dc voltage is applied to an R-C element through a Bootstrap type linearly charging circuit to form a command speed voltage smoothly and linearly increased from its null magnitude to a constant magnitude for the acceleration of an elevator car. Upon decelerating the car, the dc voltage is decreased stepwise by successively opening serially interconnected contact sets coupled to a shortcircuit resistor and applied to a unidirectional R-C element including a diode through the linearly charging circuit. An output from the element is coupled to the stepped voltage through an R-C discharge circuit to produce from the element a command speed signal smoothly and linearly decreased to its null magnitude.

The disclosed elevator speed control system accelerates an induction motor for an elevator car in accordance with a voltage dependent upon a differential signal between a command speed signal and the actual speed signal and passed through a saturation generator. The saturation generator issues a command for applying across the motor its rated voltage upon the closure of a normally open contact set disposed in it. The system includes a sensor circuit is responsive to the difference signal less than a predetermined magnitude to decrease an output from the saturation generator. Alternatively the sensor circuit may responds to a negative load on the motor exceeding a predetermined magnitude to decrease the output from the saturation generator.

A drive control for transportation systems, especially elevators or the like, improves the stopping accuracy of the elevator cabin at a storey or floor of the building. A reference value transmitter operated by a digital computer produces step-like successive travel curves and displacement path-reference values operatively associated with such travel curves and feedable to a regulation circuit. Connected with the reference value transmitter is a stop initiation device, which during initiating the stop or halting of the elevator, forms from a possible target path produced by the reference value transmitter and a target path corresponding to a target storey a target error. This target error is infed to a stop correction device connected with the reference value transmitter and the stop initiation device, which while utilizing the target error modifies by interpolation the travel curve which is to be produced by the reference value transmitter in a manner such that there is available for regulation an optimum travel curve to the target storey. An arrival correction device which further improves the halt or stop accuracy of the elevator, forms from the elevator cabin site determined at a cabin displacement path counter and the storey site of the target storey a difference which, for the purpose of further correction of the displacement path-reference value, is infed to the stop correction device. This drive control, apart from being used with elevator systems, for instance also can be employed for track-bound horizontal systems.

During the acceleration of an elevator car a command acceleration pattern in the form of frequency modulated clock pulses is counted by a first and a second counter. The first counter issues a command speed pattern. The speed pattern is integrated to calculate the distances of movement of the care which is successively stored in a random access memory at addresses determined by the speeds from the second counter, at equal increments of speed. During the deceleration the distances of movement succesively read out from the memory are compared with the residual distances to the stop floor and the second counter counts the results of the comparison down to produce an ideal speed curve. The curve supplied to the memory is also compared with the actual car speed to modify the command acceleration with the result that the actual speed follows up the ideal speed curve.