Hitachi, Ltd.

Tokunosuke Tanamachi

Kiyoshi Nakamura

Kiyoshi Nakata

Yoshio Tsutsui

Mutsuhiro Terunuma

Masato Suzuki

Eiichi Toyota

Kouji Yasuda

Satoru Inarida

Wataru Miyake

Katsuaki Suzuki

Masahiko Ibamoto

Hiroshi Narita

Takashi Tsuboi

Shigetoshi Okamatsu

Takayuki Matsui

Takeshi Ando

Syuuji Saitou

Masanori Kobayashi

An electric power translating device employs a converter for converting an AC source voltage into a DC voltage, a smoothing capacitor connected at the DC side of the converter, an inverter for inverting the DC from the smoothing capacitor into an AC and for supplying the AC to an AC motor and means for controlling the voltage, frequency or phase in the AC output from the inverter. The device further includes means for regulating at least one of voltage, frequency and phase in the AC output of the inverter based on a ripple frequency component contained in the AC output of the inverter and associated with the rectification by the converter. Whereby, beat phenomenon caused by rectification ripple is suppressed.

Control device for electric power translating device

Apparatus and method for controlling induction motor

The control system is constructed so that an inverter output frequency command is increased/decreased based on a frequency-to-time rate-of-change command, and the frequency-to-time rate-of-change command is controlled with a current control system. Further, it is also constructed so that the frequency-to-time rate-of-change command is adjusted and the current command is changed with a readhesion control system. The control system is capable of accelerating and decelerating the vehicle with a torque corresponding to an inverter output current command which is generated basically without using any rotational frequency of induction motor, and further capable of accelerating and decelerating the vehicle with a torque corresponding to a value near the limit adhesion between the wheel and the rail under a condition of occurrence of slip/skid.

Control system for electric vehicle

A control apparatus for controlling an electric vehicle, electric car, rolling stock and electric locomotives, which ensures that an inverter output frequency command for its inverter will not depend on the rotor frequency of the induction motor, but controls the inverter output current using a constant current control system, thus preventing an overcurrent, and is capable of accelerating or decelerating the vehicle at a torque precisely corresponding to a current command. The inverter output frequency command is incremented or decremented in accordance with a frequency-to-time rate-of-change command which has been updated by the current control system. Since the inverter output frequency command is adapted basically not to depend on the rotor frequency of the induction motor, and since the output current of the inverter is controlled by the constant current control system, there are such advantages according to the invention that an overcurrent is not likely to occur, and the vehicle can be accelerated or decelerated at a torque precisely corresponding to the current command.

Control apparatus for electric vehicles

In order to equalize voltage shares of DC-side voltage dividing capacitors of a three-level power converting apparatus for converting a DC voltage to a three-level AC phase voltage, there is provided an arrangement for compensating for rising and falling instances of a three-level AC voltage pulse depending on a difference voltage between the two voltage dividing capacitors and the polarity of the AC current, thereby adjusting a zero-voltage period of the AC voltage.

Three level power converting apparatus having means for balancing DC

An electric power converting apparatus equipped with a 3-level PWM control in which the output voltage can be continuously and smoothly controlled from zero to a maximum voltage. The electric power converting apparatus includes a multi-pulse generating unit arranged for a dipolar modulation, a unipolar modulation, and an overmodulation; a 1-pulse generating means; and a unit for controlling the transfer operation among these modulation regions.

Electric power converting apparatus

An electric railway vehicle control system including a converter for converting a single-phase a.c. voltage to a d.c. voltage, a PWM inverter for inverting the d.c. output of the converter to a variable voltage, variable frequency a.c. voltage, and a three-phase induction motor supplied with the a.c. output voltage of the inverter to drive electric railway vehicles. The control system further includes a unit for controlling the output voltage of the inverter in a variable voltage, variable frequency mode for changing the output voltage substantially relative to a change in the output frequency thereof and in a constant voltage, variable frequency control mode for fixing the output voltage to a substantially constant value, and a unit for detecting a rectification ripple in a frequency band including a frequency double the frequency of the single-phase a.c. voltage included in the d.c. input voltage to the inverter.

Inverter control apparatus

Disclosed is an apparatus for realizing a small apparatus by making element currents uniform in the dipolar modulation mode. The zero voltage period in the dipolar modulation period is made shorter than other voltage output periods. Accordingly, currents of switching elements constituting the main circuit of an inverter can be made uniform.

Control apparatus of power converter and control apparatus of electric

The power converter of the invention relates to a small-sized highly efficient power converter for generating an a.c. voltage output of multiple levels with less harmonic content. In the power converter, a d.c. voltage source is separated into plural sections by series connected voltage dividing capacitors and multiple levels of a.c. output voltage are obtained from the divided d.c. voltage by on-off control of switching devices. The power converter has plural sets of the voltage dividing capacitors disposed separately adjacent to each switching devices, and series connection point of each set of the voltage dividing capacitors are connected to division points of the corresponding switching devices of each phase. The voltage dividing capacitors are connected with each other at their series connection points. Thereby, the arrangement makes wiring length short and equal between the switching devices and the voltage dividing capacitors for each phase and reduce a loss in the snubber circuit, resulting in an a.c. voltage output with less harmonic content.

Multilevel inverter having voltage dividing capacitors distributed

An electrical power converter having a phase converter constituted by positive side semiconductor switching elements connected in series and negative side semiconductor switching elements connected in series which converts a DC voltage to an AC output phase voltage having at least three potential levels, resulting in three possible modulation modes: dipolar, partial dipolar and unipolar. Dipolar modulation is realized by alternating positive and negative output pulses. Unipolar modulation is realized by output pulses having only the same polarity as the corresponding fundamental modulation wave. Transition is accomplished via partial dipolar modulation which is realized by alternating positive and negative output pulses in a first period of a half cycle by outputting alternating positive and negative pulses and in a second period by outputting pulses having only the same polarity as the corresponding fundamental modulation wave. A control unit for the converter turns the semiconductor switching elements on and off depending on an input voltage amplitude command for a fundamental modulation wave. The intervals of the first and second periods in the half cycle of the AC output phase voltage varies dependent upon the voltage amplitude command.

Electric power converter arrangement and electric rolling stock control

An apparatus for a three-level DC/AC converter, in which the width of output pulse having the same polarity as the fundamental wave of the converter output phase voltage is adjusted depending upon the DC component of a differential voltage between two DC voltages in a dipolar modulation system of the converter. Whereby, the imbalance of DC components between the two DC voltages is easily and effectively suppressed.

Power converter for converting DC voltage into AC phase voltage having

The present invention relates to a control apparatus of a three-level inverter and intends to provide a control apparatus of simplified construction which can suppress a fluctuation in neutral point voltage effectively. Only a third harmonic component which is particularly large in the fluctuation in neutral point voltage is suppressed, a third harmonic component for suppression has a ratio of amplitude to that of a fundamental wave and a phase which are set to be constant regardless of the inverter frequency, and this third harmonic component is applied to a command of the fundamental wave.

Control apparatus for suppressing a third harmonic neutral point voltage

In an inverter control apparatus including a pulse width modulation inverter supplied with power from a d.c. power source to generate an a.c. output, a frequency control unit controlling the output frequency of the inverter, and a voltage control unit controlling the output voltage of the inverter, a frequency adjusting unit is provided to adjust the operating frequency of the inverter so that the product of voltage and time in each positive half cycle of the output voltage of the inverter becomes equal to that in the next adjacent negative half cycle of the output voltage of the inverter. When the inverter is used in an apparatus for controlling an induction motor, the frequency adjusting unit adjusts the output frequency of the inverter according to the result of detection of a ripple factor of an input voltage of the inverter, and a frequency adjusting-factor correcting unit corrects the frequency adjusting factor of the frequency adjusting unit according to at least one of the output of an induction-motor rotation frequency detector and the output of the voltage control unit.

Growing community of inventors

Katsuta, Japan

Tokunosuke Tanamachi