Hitachi, Ltd.

Hitachi Keiyo Engineering Co., Ltd.

Hitachi Keiyo Eng. Co., Ltd.

Hiroshi Nagase

Toshiaki Okuyama

Yuzuru Kubota

Katsunori Suzuki

Hisakazu Ninomiya

Nobuyuki Yamashita

Tadahiko Miyoshi

Kiyohiko Tanno

Yoshiyuki Yasutomi

Masahisa Sobue

Fumio Jooraku

Shoji Arimoto

Hiromi Inaba

Yasuo Matsuda

Satoshi Ibori

Nobuyoshi Mutoh

Toshihiko Matsuda

Hideki Nihei

Hiroshi Sugai

Sumio Kobayashi

Sadayuki Igarashi

Ryoso Masaki

Hiroyuki Tomita

Kunio Miyashita

Takashi Ikimi

Ichiro Nakamura

Shigeta Ueda

Yasunori Katayama

Keijiro Sakai

Hiroshi Hayashida

Masahiro Kayama

Kazuo Honda

Yasuyuki Sugiura

Nobuyoshi Muto

Takamasa Hori

Yuuji Yoshitomi

Takashi Teramoto

Kenzo Kamiyama

Rika Oue

Toshiyuki Tadokoro

Kensuke Kato

An elevator in which the sheave diameter is reduced and the attendant lowering of the rope life and strength is suppressed to secure safety and reliability. To this end, a rope is used in which a plurality of element wires constituting the wire rope are each covered with resin material and the whole wire rope is covered with resin material, thereby reducing the wear due to slippage between the element wires and the wear due to contact with the sheave, which wear occurs when the rope is entrained around the sheave. When the elevator sheave diameter is reduced, a worried lowering of the rope life can be suppressed or the rope life can be improved. Thus, it is possible to achieve reduction of size and weight of equipment including motors and hoists, installation space saving for elevators, improved safety and reliability of the system by virtue of the increased rope life.

Rope and elevator using the same

An elevator system in which an elevator-car and a counter weight are suspended on a pulley system in a hoistway. The elevator system includes a receiving unit for receiving an electric power from a feeding unit provided in the hoistway, an inverter for converting the received electric power into ac power, a motor connected to an ac side of the inverter for driving the counter weight in up and down directions, a sensor for detecting a position of the receiving unit, and a control unit for controlling an inverter on the basis of the position detected by the position sensor. The counter weight carries the receiving means, the inverter, and the motor.

Elevator

The invention provides a conductor comprising a reaction-sintered body of a conductive nitride produced from a powder of at least one metal selected from Ti, Zr, V, Nb, Ta, Cr, Ce, Co, Mn, Hf, W, Mo, Fe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, Th and Ni, and a process for producing such conductor by heating a molding containing a metal powder in a nitriding gaseous atmosphere containing no CO gas.

Conductive material and process for preparing the same

Sine wave signals generated from a position detector are used as analog values to detect a fine position of a rotating or moving body, a rise or fall edge of the sine wave signal is used to detect a coarse position of the rotating or moving body, and the position or speed of the rotating or moving body is detected based on a signal indicative of the detected coarse position when the rotating or moving body is at high speed and based on a signal indicative of the detected fine position when the rotating or moving body is at low speed to thereby provide optimal control from high speed to low speed. Especially at extremely low driving, speed detection with superhigh resolution is effected using the analog value to decrease an uneven rotation of the rotating body.

Method and apparatus for detecting positions and/or speed of a moving

An actuator suitable for use in a joint device for driving a robot arm or in a subject follow-up device in a video camera, etc., is designed to have a mobility of a freedom of two degrees or more and is adapted to drive a movable part directly using first piezoelectric motor elements each of which consists of piezoelectric elements having a non-ring-like configuration and an elastic body and second piezoelectric motor elements each of which consists of at most one ring-like piezoelectric element and an elastic member. The actuator exhibits a simplified structure, is small and lightweight, provides a powerful driving power and has a wide range of mobility.

Actuator

A control apparatus for controlling a PWM inverter, the PWM inverter receiving AC power and generating an AC output having a controlled frequency to be supplied to an AC motor, comprises a circuit for generating, on the basis of a given running command, a PWM signal controlling the inverter with a given sampling period, and a circuit for controlling the PWM signal generating circuit, whereby the AC motor generates an electromagnetic tone preselected so as to correspond to desired information when the AC motor is driven by output of the inverter controlled by the PWM signal. The above described desired information may be information representing the running state of the motor or selected music.

Control apparatus for inverter for driving AC motor

An induction motor is driven by a PWM inverter including switching elements such as gate turn-off thyristors of Graetz connection. Turn-on of the PWM inverter is controlled by PWM pulse signals generated from a pulse width modulator. The pulse width modulator includes comparators having a hysteresis characteristic which generate the PWM pulse signals on the basis of the magnitude and polarity of current errors between current command pattern signals and signals indicative of detected output currents of the PWM inverter. A signal generator generates an AC signal which is applied to the comparators so that the PWM pulse signals generated from the comparators act to increase the effective value of the neutral voltage of the output of the PWM inverter.

Method and apparatus for controlling PWM inverter

An AC motor such as an induction motor or a synchronous motor is driven by a PWM inverter. Turn-on of the PWM inverter is controlled by PWM pulse signals obtained as a result of comparison between voltage command signals (a modulation signal) and a carrier wave signal. The voltage command signals are obtained as a function of errors between current command signals and detected current signals. Ripples included in the voltage command signals are so suppressed as to be decreased as the rotation speed of the AC motor becomes lower. By so suppressing the ripples, the level of noise generated from the motor can be reduced especially when the motor operates in a low-speed rotation range.

A control apparatus for an induction motor wherein an inverter is connected between a power source and the induction motor so as to energize the induction motor through the inverter, characterized in that when an input voltage of the inverter has lowered, a magnetizing current component command is decreased, while a torque current component command is increased.

Control apparatus for induction motor

An induction motor is driven by a converter which outputs a variable frequency and variable phase A.C. voltage. The frequency is instructed by a signal which corresponds to a difference between a detected speed signal and set speed signal, a signal which corresponds to a difference between a detected magnetic flux intensity signal and set flux signal, and the detected speed signal.

Method and apparatus of controlling induction motors

When driving an AC motor with a PWM inverter, the width of a speed command signal is modulated by a carrier to produce width modulated pulses for controlling main switching elements. The width modulated pulses are liable to be attended with impulses which cause magnetic vibrations in the AC motor, resulting in noises. The generation of these impulses can be suppressed by changing the amplification factor of an amplifier for the speed command signal or the amplitude of the carrier on the basis of the rate of change of the speed command signal. Noises which would be attendant on low speed running of the AC motor can be reduced by changing the amplification factor of the amplifier and the amplitude of the carrier on the basis of detected frequency of the speed command signal or revolution of the AC motor during low speed running.

Control apparatus for AC motors

In a converter comprising gate turn-off thyristors, a current at an A.C. part of the converter is detected and a polarity of the detected current and a magnitude of the detected current is checked to determine if it is below a holding current level for maintaining the gate turn-off thyristors on. If the detected current is below the holding current level, a pulse width modulated signal is produced as a gate signal. If the detected level is above the holding current level, a short duration pulse synchronized with a rise and a fall of the pulse width modulated signal is produced as the gate signal. The gate signal is supplied to only those of the gate turn-off thyristors which correspond to the polarity of the detected current.

PWM Converter with control circuit responsive to minimum holding current

A control apparatus for induction motor comprising an induction motor driven by a power converter, a circuit for producing an effective current command value for the induction motor on the basis of a speed command value and an actual speed value, a circuit for producing a slip frequency corresponding to the magnitude of the effective current command value, and a circuit for producing a primary frequency command value on the basis of the slip frequency and the actual speed value, the output of the power converter being controlled on the basis of the frequency command value, the effective current command value and a given exciting current or voltage command value, wherein the control apparatus further comprises a current component detecting circuit for detecting the primary current of the induction motor so as to produce in the form of a DC signal an actual effective current value which is an effective component of the detected primary current, a first current control circuit for producing an effective voltage command value in the form of a DC signal on the basis of the actual effective current value and the effective current command value, and a converter controlling circuit for controlling the power converter to produce output on the basis of the effective voltage command value, the frequency command value, and a given exciting voltage command value in the form of a DC signal. The current component detecting circuit preferably further produces in the form of a DC signal an actual exciting current value which is an exciting component of the detected primary current, and the controlling apparatus may further comprise a second current controlling circuit for producing the exciting voltage command value on the basis of the actual exciting current value and the predetermined exciting current command value.

Method for controlling induction motor and apparatus therefor

Growing community of inventors

Hitachi, Japan

Hiroshi Nagase