Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Seiya Shima

Hiromi Inaba

Toshiaki Kurosawa

Takeki Ando

Sadao Hokari

Hiroaki Kuroha

Yoshio Sakai

Nobuo Mitsui

Korefumi Tashiro

Shigeta Ueda

Mutsuhiro Terunuma

Takanobu Hatakeyama

Katsu Komuro

Yasunori Katayama

Mitsuyuki Hombu

Toshimitsu Tobita

Akiteru Ueda

Tomiaki Kurihara

Hideaki Takahashi

Katsunori Suzuki

Nobuyoshi Tsuboi

Kenji Yoneda

Masao Nakazato

Kazuo Honda

Kazuhiro Sakata

Mitsuyuki Honbu

Toshisuke Mine

Hayashi Nakazawa

Yasuyuki Maeda

Morio Kanasaki

Kunio Saito

Toshio Meguro

Hajime Nakashima

Kazuhiko Sasaki

Toshiro Narita

Hiromi Inabe

Ando Takeki

Hideo Miyao

Katuhito Issiki

Control signals for operating power converter switching elements are created using one-chip microcomputers. Pulse patterns required to supply the control signals and their generating timings are previously created and scheduled in pairs. When the times when the control signals are to be supplied to the switching elements have actually come, those control signals are successively output.

Method and apparatus for controlling power converter

A pulse generator (including a microcomputer) for supplying a pulse pattern to semiconductor devices of a power converter (such as an inverter or a converter) using the pulse width control scheme is provided with function of dropping pulses so that the pulse pattern may form a predetermined function provided that the pulse width is shorter than a limit value (Limit). As a result, the input and output waveforms of the power converter can be made sinusoidal and can be released from the constraint of the minimum pulse width of power conversion semiconductor devices.

PWM control for power converter system utilizing pulse dropping at

In a three phase inverter which is composed of transistors turned on or off in accordance with the PWM control, the pulse widths of PWM gate signals for the transistors are determined in accordance with the magnitudes of two of the three phases of the current to be output by the inverter. The load of a processor for generating the gate signals can be reduced to the great extent, and in addition thereto, the waveform of the output current of the inverter is much improved.

Apparatus for controlling power transducers of the pulse width

A first apparatus for determining instantaneous reactive currents to determine instantaneous reactive currents in every phase of a three-phase load. Three phase current signals corresponding, respectively, to phase currents of the three-phase load supplied from a three-phase power-supply source are multiplied with sinusoidal wave signals of three phases, each of which has a phase difference of 90.degree. relative to the corresponding phase voltage of the three-phase power supply source to obtain the products for three phase, respectively, which products are added together to produce a sum signal. The instantaneous reactive currents mentioned above are determined on the basis of the sum signal and the three phase sinusoidal wave signals. A second apparatus for compensating the reactive power of the three-phase load by means of a converter load circuit including a current-source type three phase converter connected in parallel with the three-phase load by making use of the instantaneous reactive currents of the three-phase load determined by the first mentioned apparatus.

Apparatus for compensating reactive power by current-source type

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

A current-source power converting apparatus having a three phase AC-DC converter composed of self-extinction devices for converting an AC power furnished from an three phase AC power source into a DC power and a DC-AC inverter connected with the AC-DC converter through a DC reactor for re-converting the DC power into a three phase AC power to supply the re-converted power for a load. When the failure of the AC power source is detect according to one embodiment, the AC power source is detached from the AC-DC converter and a battery is connected between arbitrary two phases at the input end of the AC-DC converter. After that, the DC power of the battery is supplied for the DC-AC inverter intermittently by switching the corresponding self-extinction devices of the AC-DC converter and controlled by varying the duty ratio of the switching operation.

Current-source power converting apparatus with self-extinction devices

A dv/dt protection circuit device for an AC-DC converter apparatus including control board switching arrangement having a current cut-off function which conducts an interrupts current from a power source to a load and refluxes the load current while the current is uninterrupted by a full-wave bridge rectifier circuit having a plurality of arms. Each arm of the bridge rectifier circuit connects a reactor for suppressing a rate of change of a power source line voltage of the bridge rectifier circuit at the switching time of the switching arrangement and a condenser is provided for absorbing an overvoltage generated at an inductance on the side of the power source, the condenser being connected on the side of the power source connected to the bridge rectifier circuit.

dv/dt Protection circuit device for an AC-DC converter apparatus

An elevator controller which uses an acceleration command signal that has as its initial value a start shock compensation torque which will offset the unbalance torque caused at the time of starting. From the completion of elevator car acceleration to the start of deceleration, the acceleration command is gradually increased or decreased to control the motor so as to provide a smoother motion of the car. After the inception of the car deceleration a velocity command is issued which decreases with the reducing distance between the car and the destination floor.

Controller for elevator

A control apparatus for a passenger conveyor driven by a three-phase induction motor which is capable of being put selectively into a star-connection or a delta-connection mode. A load of the conveyor is detected on the basis of a current and a voltage supplied to the induction motor, so that when the load is large the motor is driven in the delta-connection mode while when the load is small the motor is driven in the star-connection mode so as to save the power consumption of the conveyor when the load is small.

Control apparatus for passenger conveyor

In an AC elevator system employing a three-phase induction motor for driving an elevator car, the primary voltage supplied to the induction motor is controlled to control the motoring torque in the acceleration mode and in the rated-speed running mode, while, in the deceleration mode, a power converter unit supplies AC power of low frequency to the induction motor to apply regenerative braking.

AC Elevator control system

A pulse generator is coupled to a car drive motor directly coupled to a sheave, over which a rope suspending an elevator car is passed, and the position of the car is calculated through the counting of pulses produced from the pulse generator. First and second car position detectors for detecting respective first and second car positions are provided within a hatchway, and the number of pulses produced during a period from the actuation of the first car position detector till the actuation of the second car position detector is detected. A count value for calculating the car position is corrected according to the difference between the detected pulse number and a reference pulse number corresponding to the distance between the first and second car position detectors, thereby effecting the compensation for the wear of the sheave and rope to improve the precision of the car position detection.

Method and apparatus for detecting elevator car position

A power converter for power conversion between an a.c. system and a d.c. system includes a full-wave bridge circuit having GTO connected in at least one arm of the full-wave bridge circuit on the positive polarity side. During a conduction-enabled period of GTO which is determined by a firing phase angle, the GTO is so controlled as to perform current chopping operation by a pulse signal of a predetermined pulse width.

Power converter apparatus

A speed control system for an elevator motor, comprising a D. C. motor for driving an elevator, a device which generates a speed command signal for the elevator, a speed dynamo which generates a speed signal corresponding to a speed of the elevator, a speed control device which adjusts an applied voltage to the motor according to the speed deviation between the speed command signal and the speed signal, an emergency stop device which subjects the elevator to braking when the speed deviation has exceeded a predetermined value, and a blind sector device which provides an output when the speed signal has exceeded a predetermined value and which negatively feeds it back to the speed control device.

Speed control system for a motor

A safety apparatus for an elevator system is disclosed in which upon detection an instantaneous power service interruption, an emergency brake is applied to the car and continues to be applied for longer than the time required for the particular car to stop.

Safety apparatus for elevator system

In a power converter system wherein each thyristor of a three-phase full-wave bridge circuit having thyristors connected in all of bridge arms is fired for its controlling to thereby control the dc output voltage, when the dc output voltage is low, the firing angle of a group of thyristors on the negative side is fixed to a large value and the firing angle of a group of thyristors on the positive side is rendered variable within a small range so that a period may occur through which two thyristors connected in series in the full-wave bridge circuit are fired simultaneously. When the dc output voltage is high, the firing angles of groups of thyristors on both the positive and negative sides are made equal to each other and varied simultaneously. The system improves power factor and form factor over the entire controlling range of the dc output voltage.

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Katsuta, Japan

Seiya Shima