Hitachi, Ltd.

Tadao Kameyama

Katsu Komuro

Nobuo Mitsui

Yasuyuki Maeda

Sadao Hokari

Takanobu Hatakeyama

Akinori Watanabe

Yuzaburo Iwasa

Takeshi Ohira

Chihiko Honzyo

An elevator car control apparatus is disclosed in which a three-phase AC tachometer generator is coupled to a motor for driving an elevator car, and the AC output of the tachometer generator is full-wave rectified for use as a speed feedback voltage. A waveform-shaping circuit generates one pulse for each cycle of the output of the AC tachometer generator. A counter counts such pulses after the car has passed a deceleration-initiating point, thereby producing the number of counts proportional to a car running distance after the passage of the deceleration-initiating point. From this number of counts, a deceleration command voltage decreasing progressively in accordance with car positions is obtained by a decoder and a digital-analog converter. During deceleration, the car-drive motor is subjected to feedback control in accordance with the difference between the speed feedback voltage and the deceleration command voltage, thus effecting deceleration control of the elevator car.

Elevator control apparatus

In a three phase load controlling system two bilateral switching circuits control the current in the first and the third phases; the first phase is later than the third. The second phase is uncontrolled. The gating signals applied to the bilateral switching arrangement connected in the first phase are advanced by a constant degree with respect to the voltage of the first phase. The gating signals applied to the bilateral switching arrangement connected in the third phase are synchronized with the voltage of the third phase.

Three phase controlling system

In an a-c elevator, an elevator car suspended by ropes is driven by an induction motor for vertical movement. A system commonly used for controlling the device including thyristors connected in parallel with opposite polarities across a three-phase a-c power source and the induction motor for controlling the motoring torque produced by the induction motor, a bridge rectifier including a thyristor for supplying direct current to the induction motor for controlling the braking torque produced by the induction motor, and means for controlling the operating phase of the thyristors in the thyristor device and the thyristor in the bridge rectifier depending on the error between the instructed speed and the actual speed of the elevator car. When the elevator car stops at a target floor and passengers get on and off the elevator car, the variation in the load of the elevator car results in an increase or decrease in the length of the ropes thereby giving rise to an error between the floor level of the target floor and that of the elevator car. A levelling apparatus is provided which comprises a position detector detecting this level error in either direction, and a level correction speed pattern signal generator generating a level correction speed pattern signal in response to the appearance of an output from the position detector, so that the operating phase of the thyristors in the thyristor device and the thyristor in the bridge rectifier can be controlled depending on the error between the level correction speed pattern and the actual speed of the elevator car.

Levelling apparatus for AC elevator

Growing community of inventors

Ibaraki, Japan

Tadao Kameyama