Hitachi, Ltd.

Takashi Tsuboi

Hiroshi Narita

Masahiko Ibamoto

Shigetoshi Okamatsu

Akira Horie

Kyozo Tachibana

Kiyoshi Nakamura

Eiichi Toyota

Mitsugu Matsutake

Tokunosuke Tanamachi

Michimasa Horiuchi

Hiroyuki Akiyama

Eiji Kozu

Hiroshi Itahana

Ken Itoh

Kaoru Tamura

Syuuji Saitou

Yoshio Nozaki

Shozuchi Miura

Yoshinori Usui

Takao Goto

Shigeru Hatano

Fujimaro Imaizumi

Nobuaki Otazawa

Toru Higuchi

Takayuki Matui

Tadashi Kamada

Taro Uchii

Mitsuyoshi Hasegawa

In order to reduce an induction problem, which might otherwise be caused by a higher-harmonic current leaking to the outside of an inverter device, with a simple construction, an inverter device casing and a heat receiving plate mounted thereon are insulated from each other, and the heat receiving plate and a filter capacitor in the power supply circuit are connected through a predetermined inductance. Since the higher harmonics current is bypassed to the filter capacitor through the resonance filter which is formed by of the electrostatic capacity in a switching element and the inductance, the induction problem can be reduced by simple construction.

Power converting device for reducing an induction problem

A vacuum circuit breaker particularly suitable for use in an electric motor vehicle. The circuit breaker includes a vacuum interrupter to which a voltage is applied, the series combination of a capacitor and a switch which are connected in parallel with the vacuum interrupter, a provision for charging the capacitor with a voltage opposite the voltage applied to the vacuum interrupter, and a resistance connected in parallel with the vacuum interrupter. The vacuum interrupter, the resistance, and the series combination of the capacitor and switch form oscillation circuit having an oscillation frequency at least 2 KHz and an inductance of at least 1 .mu.H, with a commutating current of at least 5000 A for consuming energy stored in the circuit. In one embodiment, a capacitive element is connected in parallel with the resistor, and the length of the closed circuit include the vacuum interrupter and the capacitive element is shorter than the length of the closed circuit including the vacuum interrupter, the first capacitor, and the switch. Likewise, where no capacitive element is included, the length of the closed circuit including the vacuum interrupter and the resistance is shorter than the length of the closed circuit including the vacuum interruptor, the capacitor, and the switch. The resistance can be a linear or a nonlinear resistor, or the parallel combination of a linear resistor and a nonlinear resistor.

D.C. vacuum circuit breaker for an electric motor vehicle

A semiconductor device is provided which includes first and second semiconductor elements of different types stacked alternately. A plurality of cooling members are each disposed between the paired first and second semiconductor elements located adjacent to each other for cooling the semiconductor elements and electrically connecting the elements to each other. In other words, the cooling members will have one of the first semiconductor elements on one side and one of the second semiconductor elements on the other side. At least one connecting conductor is provided for connecting at least one of the first semiconductor elements and at least one of the second semiconductor elements in an anti-parallel connection and also for connecting a plurality of the anti-parallel connections in series to one another. Because the first and second semiconductor elements are of different types from one another which are placed under a maximum load at different times, the cooling members will not be subjected to a maximum load on both sides at the same time. Therefore, the size of the cooling member can be decreased because it will only have to provide maximum cooling to one of the first and second semiconductor elements at a time.

Power semiconductors connected antiparallel via heatsinks

A reverse-conducting GTO thyristor comprises a gate turn-off thyristor and a diode which are formed on a single semiconductor substrate so as to have a common layer and be connected electrically in an inverse-parallel connection. A power converter is composed of a plurality of pairs of these reverse-conducting GTO thyristors connected in series, each pair of thyristors being controlled so that they are turned on and off in opposite phases. An OFF gate pulse for one of each pair of thyristors continues from a time on or after the generation of an ON gate pulse for the other thyristor to the time when a recovery current flowing through the diode portion of the first thyristor is extinguished. The thus-extended OFF gate pulse functions to prevent any displacement current flowing through the GTO portion of the first thyristor during the recovery time for the diode portion thereof.

Method and apparatus for controlling reverse-conducting GTO thyristor

A sine wave of a frequency to be generated in an inverter is compared with a triangular wave having a frequency N times (N: 15, 9, 3, 1) the frequency of the sine wave, so that a modulated pulse train is generated thereby to control the inverter. This inverter supplies power to an induction motor. With the increase in motor speed, N is reduced until it finally becomes 1. When the inverter transfers from an idle state to an active state, N is inhibited from becoming 1 but set to 3 even if the motor is running at high speed.

Induction motor control system and method

A control system for an electric motor vehicle adapted to be driven by a group of induction motors, comprises a converter for producing an a.c. output to energize the group of induction motors, a frequency command circuit for producing a value representing a minimum number of rotations among those of at least two induction motors of the group added with a slip frequency in a power running mode of the vehicle on one hand and a value representing a maximum number of revolutions among those of at least two given induction motors of the group subtracted by the slip frequency in a regenerative braking mode, respectively, the values being utilized as frequency control commands, and a frequency control circuit for controlling the output for controlling the output frequency of the converter in dependence on the frequency control commands, thereby to improve the adhesion performance of the electric motor vehicle.

Control system for electric motor vehicle

A control apparatus is disclosed for an electric car having an induction motor supplied with polyphase AC power of variable frequency from a power converter so as to drive a driving wheel. This control apparatus comprises a detector for detecting the actual running speed of the electric car irrespective of whether the driving wheel causes adhesion or non-adhesion, a device for establishing a slip frequency of the induction motor, and a device for generating a frequency command based upon a signal of the actual running speed and the slip frequency, this frequency command being used to control the output frequency of the power converter.

Control apparatus for electric car

In an electric car, wherein the powering drive and the braking drive are executed by on-off controlling a current through a d. c. motor by means of a chopper, when the electric car is below a predetermined speed, a field coil of the d. c. motor is put into a series winding connection so as to carry out full field control, and when the car is above the predetermined speed, the field coil of the d. c. motor is changed-over to a shunt winding connection so as to carry out weak field control. The duty cycle of the chopper is controlled with the running state of the electric car taken into consideration in order that the field current at the time when the series winding connection has been changed-over to the shunt winding connection may become substantially equal to a value before the change-over, whereby the transient change of the current between before and after the change-over of the field coil is suppressed.

Control apparatus for an electric car

This invention is applied to a power converter with a converting apparatus comprising one or more units including only controlled rectifiers or combination of controlled rectifiers and non-controlled rectifiers, said converting apparatus being connected with an AC power source, whereby high harmonic currents generated in the AC circuit during commutating periods are reduced. In the present invention, at the commutating period of the converting apparatus, the reactance in the AC circuit of the converter is changed to increase in accordance with change of the AC current of the converting apparatus, so that the change of the AC current during the commutating period is made more slowly thereby reducing high harmonic currents.

High harmonic current reducing apparatus in power converter

In a linear motor system in which the series of driving coils provided along a railway is divided into sections each including a plurality of coils, each section being fed through a power control switch which is closed in a sequential order, a plurality of such sections are grouped so that each group of sections is fed exclusively through one of a plurality of feeders from one of a plurality of power supplies.

Power supply system for a linear motor

A power converter system for converting an AC voltage into a DC voltage, comprising a transformer means provided with a primary winding connected to an AC power source and a secondary winding divided into a plurality of sets of coils; and rectifier means including a plurality of rectifier circuits, each of said rectifier circuits including controlled rectifier elements and having AC and DC terminals, said AC terminals of each rectifier circuit being connected to the corresponding one of the sets of secondary coils, said DC terminals of said respective rectifier circuits being connected in series to produce a DC output voltage from said rectifier means, a predetermined one of said rectifier circuits being adapted to control its DC output voltage sequentially and cyclically in a plurality of steps of generating the DC output voltage from said rectifier means, the remaining rectifier circuits being adapted to control their DC output voltages in an on-off fashion in said steps, said steps being switched over by on-off controlling said remaining rectifier circuits for on-off control when the DC voltage of said predetermined one of said rectifier circuits reaches an ultimate value in each cycle; the improvement wherein a voltage control range of the predetermined one of the rectifier circuits for sequential control is selected to overlap voltage control ranges of the remaining rectifier circuits for on-off control.

Power converter system

A static power converter includes a plurality of thyristor bridges. The level of the control voltage is measured and a signal representative of the measured level is generated which causes one thyristor bridge to maintain a substantially zero output D.C. voltage, while another thyristor bridge operates with phase shift control.

Static power converter controlling apparatus for reducing noise

An electric braking control apparatus for the DC motor comprises; a DC power supply; a series circuit including the field winding and armature of a DC motor a smoothing reactor and a resistor connected to the DC power supply; a chopper connected in parallel to the series circuit, and a diode inserted between the DC power supply and the parallel circuit including the series circuit and the chopper. The field winding and the resistor are regulated in effecting regenerative braking of the DC motor by turning on and off the chopper.

Electric braking control apparatus for DC motor

A regenerative brake control system for controlling an armature current of DC motor by on-off operation of a chopper through resistor means which is connected in series with the DC motor and is appropriately divided into sections is disclosed. In the system, the notching operation of the resistor means is controlled in such a manner that the duty cycle of the chopper immediately following the short-circuiting of one section of the resistor means is to be the minimum value tolerable to the chopper.

Regenerative brake control system for DC motor

A control system for an A.C. motor which is connected to the output terminals of a thyristor inverter, a capacitor is connected between the D.C. input terminals of the thyristor inverter, and the respective thyristors constituting the inverter are extinguished by self commutation due to an oscillating current produced by the capacitance of the capacitor and the reactance component of the armature coils of the A.C. motor connected to the A.C. output terminals of the thyristor inverter, and a current in the waveform of pulses produced by electric oscillation is delivered in a predetermined phase sequence to the armature coils of the A.C. motor.

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Katsuta, Japan

Takashi Tsuboi