Hitachi, Ltd.

Akiteru Ueda

Nobuyoshi Mutoh

Keijiro Sakai

Kenji Nandoh

Yoshio Sakai

Satoshi Ibori

Shigeta Ueda

Seiya Shima

Mitsuyuki Hombu

Takeki Ando

Toshiaki Kurosawa

Motonobu Hattori

Hideyuki Shimonabe

Ikuo Okajima

Akira Ishibashi

Hiroshi Fujii

Katsunori Suzuki

Keiichi Mashino

Hiromi Inaba

Katsuji Marumoto

Hiroshi Narita

Masao Nakazato

Hisakatsu Kiwaki

Toshio Suzuki

Kazuo Honda

Katsu Komuro

Mitsuyuki Honbu

Nobuo Mitsui

Hidetoshi Aizawa

Ryuji Iyotani

Yuuzi Yamasawa

Kazuhiko Sasaki

Hajime Nakashima

An electric power converter comprising a plurality of reactors, a plurality of self quenching type switching elements, the reactors and switching elements being series-connected per one arm, and surge-absorbing snubber circuits connected in parallel to the switching elements respectively, the switching circuits being driven by gate drive circuits connected to respective gates of the switching elements to thereby convert a DC voltage into an AC voltage or convert an AC voltage into a DC voltage. The electric power converter further comprises: an apparatus for recovering energy accumulated on at least one side of the reactors and the snubber circuits and an apparatus for generating a DC source for supplying electric power to each of the gate drive circuits, on the basis of the recovered energy. In the electric power converter constituted by a plurality of self quenching type semiconductor switching elements connected in series, high efficiency is attained through reduction in size of the gate driver and electric power saving.

Gate drive power source for electric power converter

A charging generator output control system for automobiles is disclosed, in which the field current of the generator is controlled by a chopper, an output voltage of the generator is compared with a predetermined target voltage, the difference therebetween is detected, and the duty factor of an output signal of the chopper is controlled in accordance with the difference while at the same time controlling the frequency of an output signal of the chopper in accordance with the duty factor, thus reducing the difference substantially to zero.

Control system for automotive charging generator

A PWM inverter apparatus used for driving an a.c. motor, including an inverter having an output part connected to the a.c. motor and switching elements on-off controlled by a PWM signal. The inverter apparatus also includes a part for receiving, at an interval of a given sampling period, status command information specifying a desired status of a vector of a rotating magnetic flux in the a.c. motor; a part for predicting, on the basis of at least the status command information received at each sampling time, the status of the vector of the rotating magnetic flux which will be produced at a next sampling time; a part for calculating a difference vector between the status of the vector of the rotating magnetic flux specified by the status command information received at a present sampling time and the predicted status of the vector of the rotating magnetic flux which will be produced at a next sampling time; a part for synthesizing the difference vector using selected reference voltage vectors from among a plurality of predetermined reference voltage vectors; and a part for generating a PWM signal for controlling the switching elements of the inverter so as to produce the selected reference voltage vectors.

PWM inverter apparatus for controlling rotating magnetic flux in a.c.

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 method and apparatus are disclosed for controlling a pulse width modulated (PWM) inverter controlled for ignition by a (PWM) pulse produced with a carrier wave and a modulation wave. The method comprises sampling an amplitude of the modulation wave at a cycle rate related to the frequency of the carrier wave. The modulation wave and the carrier wave are synchronized when the sample modulation wave amplitude has a peak value greater than an amplitude of the carrier wave. The modulation wave and the carrier wave are asynchronized when the sampled modulation wave has a peak value less than the amplitude of the carrier wave.

Method and apparatus for selectively controlling an operation mode of a

A control system for controlling a PWM inverter so that the inverter drives an induction motor at a variable voltage and a variable frequency while keeping constant a ratio of the output voltage of the inverter to the output frequency thereof, is disclosed which includes current component detecting means for detecting an effective current corresponding to a load, from the input current of the induction motor, frequency setting means for setting the output frequency of the PWM inverter, flux setting means for setting the amount of magnetic flux generated in the induction motor, correcting-frequency calculating means for calculating a frequency correcting quantity proportional to the effective current, and correcting-flux calculating means for calculating a flux correcting quantity proportional to the effective current. In a case where the detected effective current is judged to be less than a predetermined value, the frequency correcting quantity is added to the set output frequency to obtain an output frequency command, and the sum of the flux correcting quantity and the set amount of magnetic flux is multiplied by the value of the output frequency command to obtain an output voltage command, for the purpose of controlling the operation of the PWM inverter on the basis of the output frequency command and the output voltage command.

Control system for PWM inverter

A single phase, full wave diode bridge circuit is connected with a chopper on its DC output side. An output voltage of the chopper is smoothed by a smoothing capacitor and thereafter supplied for a load. A current control apparatus forms a current reference signal which is synchronized with an AC voltage applied to the bridge circuit and has a magnitude corresponding to a current flowing through the load and produces a deviation signal between the current reference signal and an actual AC input current of the bridge circuit. The chopper is controlled in accordance with the deviation signal so that the AC input current follows the current reference signal, whereby the power factor and the waveform of the AC input current in the bridge circuit are improved.

Rectifier control apparatus with improved power factor

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

In an elevator wherein an elevator cage is repeatedly run among a plurality of floors by controlling a cage driving motor in accordance with a velocity command; a floor arrival error involved when the elevator cage has arrived at the floor is detected, and the velocity command for the subsequent operation is corrected in accordance with the floor arrival error, thereby to enhance the floor arrival precision.

Elevator control apparatus

An AC motor such as an induction motor or a synchronous motor is driven by a PWM inverter circuit. Power switching elements of the inverter circuit are ignited by PWM pulses resulting from comparison of a carrier wave signal with a sine wave modulation signal at a frequency proportional to a frequency setting signal so as to control the inverter circuit. A current polarity detector detects positive and negative components of a DC current flowing in the input side of the inverter circuit. The frequency setting signal is so corrected as to be decreased when only the positive current component flows in excess of one period of the carrier wave signal or increased when only the negative current component flows in excess of the one period.

Method and apparatus for controlling PWM inverters

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Ibaraki, Japan

Akiteru Ueda