Hitachi, Ltd.

Kazuhiko Sasaki

Shigeta Ueda

Takeki Ando

Hideaki Takahashi

Yoshio Sakai

Seiya Shima

Mitsuyuki Hombu

Toshiaki Kurosawa

Masao Nakazato

Kazuo Honda

Akiteru Ueda

Katsu Komuro

Mitsuyuki Honbu

Nobuo Mitsui

An elevator control apparatus comprises an inverter device for supplying an induction motor for driving an elevator cage with AC electric power of variable voltage and frequencies and control equipment for controlling the output voltage and frequencies of the inverter device in response to signals produced in floors served by the elevator and in an elevator cage. The inverter device is constructed by a converter unit for converting AC electric power to DC electric power, at the input end of which a capacitor is connected in parallel with an AC electric source, an inverter unit for inverting the DC electric power converted in the converter unit into AC electric power, at the output end of which a capacitor is connected in parallel with an induction motor for driving the elevator cage and a DC reactor connected between the converter unit and the inverter unit. The thus constructed elevator control apparatus does not cause interference in electric appliances such as audio equipment, computer etc. existing within a building in which the elevator is installed.

Apparatus for controlling AC elevators

In a current-type converter system in which a DC current is fed to a load through a pulsating current suppressing DC reactor from a current-type converter constituted by self-extinction elements connected in a bridge circuit, a converter protection apparatus is arranged such that when a fact that a terminal voltage of the DC reactor becomes an overvoltage is detected, the self-extinction elements are turned on so as to form a closed circuit including the DC reactor, the load, and the converter so that the overvoltage can be suppressed and continuous operation of the converter can be carried out.

Current-type converter protecting apparatus

Growing community of inventors

Katsuta, Japan

Kazuhiko Sasaki