Apparatus for controlling the speed of an elevator

Details Apparatus for controlling the speed of an elevator Apparatus for controlling the speed of an elevator

1984-11-20

1986-07-29

Shoop, Jr., William M.

Elevator, industrial lift truck, or stationary lift for vehicle

Stationary lift for roadway vehicle or required component...

Having specific drive means for support

B66B 130

Patent

active

046027017

ABSTRACT:
An apparatus for controlling the speed of an elevator, which controls an AC electric motor that drives the cage, by using a power rectifier made up of thyristors and a power inverter made up of a transistor and a diode. A speed instruction for the cage is compared with a detected speed to produce an output instruction signal for said power rectifier and a slip frequency instruction signal for said power inverter. A control circuit controls the phase of said power rectifier relying upon the output instruction signal and controls the pulse-width modulation of said power inverter relying upon said slip frequency instruction signal, the control circuit comprises a voltage detector that detects the voltage of the AC power source, and a minimum value select circuit that receives the output of said voltage detector as a first input, that receives said output instruction signal as a second input, that compares these inputs, and that produces a signal of the same level as the signal of the lower level. The output of said minimum value select circuit is produced as a corrected output instruction signal to control the phase of said power rectifier.

REFERENCES:
patent: 4482031 (1984-11-01), Yoshida et al.
patent: 4519479 (1985-05-01), Tanahashi

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