Hitachi, Ltd.

Kawasaki Steel Corporation

Masahiro Tobise

Takashi Okada

Yoshitaka Iwaji

Yasuo Morooka

Hiromi Inaba

Kenichi Onda

Takashi Ikimi

Kenji Kubo

Takashi Nakahara

Kiyoshi Sakamoto

Toshihiko Matsuda

Tsutomu Omae

Noboru Azusawa

Hirohisa Satomi

Daisuke Tan

Itsuo Shimizu

Takashi Sukegawa

Toshihiko Chino

Rached Dhaouadi

Hiromasa Kogure

Tadahiko Kanbara

Hiroshi Koseki

Yuji Yamasawa

Kiyotaka Kobayashi

Kazumi Ebihara

Yoshitaka Yoshinari

Hisayuki Matsumoto

An object of the present invention is to provide a power converter in which the open-phase can be detected in a broader frequency region even if a predetermined relation is kept between the output voltage and the frequency. In order to achieve the above objects, a power converter including: an inverter unit having phase unit inverters provided with a plurality of multiple connected single-phase cell inverters for every phase; an inverter controller for controlling the inverter unit so that a predetermined relation is kept between an output voltage and a frequency; and a plurality of transformers for detecting output voltages of the plurality of phase unit inverters, in which the inverter controller is provided with a fault detection unit for detecting whether a phase-to-phase voltage deviation calculated by the output voltage is within range of an allowable voltage deviation calculated as a function of the frequency is provided.

Power converter and motor driving system

A control system for determining a control function for a control device on the basis of a transfer function of an object to be controlled and for adjusting an operation quantity of an object to be controlled in accordance with the determined control operation function, wherein an control function of a first control device is determined so that a closed-loop transfer function of a control system including the object to be controlled and the first control device coincides with a predetermined first transfer function, an control function of a second control device is determined, in a closed loop control system including the control system and the first control device, so that a transfer function from a disturbance applied to the object to be controlled to a state variable of a point at which the disturbance is applied to the object to be controlled, and a sum signal indicative of a sum of outputs of the first and second control devices is used as an operation quantity of the object to be controlled.

Control system and method

In order to provide a power inverter device which can reduce surge voltages in all of the operating conditions thereof and has a simple structure, in a neutral point clamped 3 level type power inverter device formed by connecting semiconductor switching elements, diodes and smoothing use capacitors connected via plate shaped conductors, a first plate shaped conductor connects the diodes and the smoothing use capacitors and a plurality of plate shaped conductors connecting the elements are disposed over the first plate shaped conductor and separated from it by an insulating material.

Power inverter device

A motor controller includes a shaft torsion vibration estimator for estimating a shaft torsion vibration between a motor and a mechanical load and a shaft torque estimator for estimating a shaft torque acting upon a motor shaft, wherein a vibration in a mechanical load driving system is suppressed by utilizing an estimated shaft torsion torque value calculated by the shaft torsion vibration estimator and an estimated shaft torque value calculated by the shaft torque estimator in addition to a detected motor speed value. Using such a system stable speed control having improved response can be achieved since higher order vibration modes can be suppressed without deteriorating its shaft torsion vibration without deteriorating its shaft torsion vibration suppression performance by combining the shaft torsion vibration estimator and the shaft torque estimator.

Motor speed controller for suppressing shaft torsion vibration

A speed control method and apparatus for a motor driven by output of a power conversion unit, wherein a first current command value is inputted to derive a drooping variable, a deviation between a detected speed value of the motor and a speed command value is derived, the first current command value is derived on the basis of a value obtained by compensating the deviation with the drooping variable, the speed command value is inputted to derive an acceleration or deceleration current value for accelerating or decelerating the motor, and the first current command value and the acceleration or deceleration current value are added together to derive a second current command value and control the output current of the power conversion unit on the basis of the second current command value.

Motor speed control method and apparatus with drooping compensation

A plant controller calculates the updated value of a control parameter for a motor controller for controlling motors for driving process machines in accordance with the change in the operational condition of a process plant so as to transmit it to the motor controller. The motor controller updates the set value of the control parameter relating to the control characteristics of the motor in accordance with the supplied updated value of the control parameter. The plant controller transmits the updated value of the control parameter to the motor controller in such a manner that the parameter code denoting the type of the control parameter and the updated value are allocated to predetermined bits of one word. The motor controller separates the received parameter code and the updated value from each other to change the setting of the control parameter, which corresponds to the parameter code, in accordance with the updated value.

Control system

A speed control apparatus for a motor comprising a motor model formed of a motor current model and a motor speed model connected in cascade, a basic torque instruction signal being applied to the motor model, and first and second control loops comparing output signals from the motor current model and the motor speed model with an instantaneous actual motor current signal and an instantaneous actual motor speed signal respectively and generating first and second correction signal to be added to the basic torque instruction signal to form a corrected torque instruction signal which is applied to a motor current control circuit, whereby a speed oscillation is suppressed even when the motor is driving an oscillatory load.

Speed control apparatus for motor

In a static leonard apparatus, a DC motor is supplied from a thyristor converter through a main circuit switch, and a capacitor is connected between the DC output buses of the thyristor converter. When the main circuit switch is turned off, a grounding switch is turned on to ground one of the DC output buses to form a grounded closed discharge circuit including the DC motor through which the capacitor discharges. During the turned-off period of the main circuit switch, the capacitor is charged with the output voltage of the thyristor converter. The capacitor discharges through the grounded closed discharge circuit. The voltage values of the discharging capacitor at two points on the time axis are detected to compute the discharge time constant of the capacitor, and, on the basis of the computed discharge time constant, the insulation resistance of the DC motor is measured.

Insulation resistance measurement in static leonard apparatus

In a converting device having two sets of converters, each of which includes planar type semiconductor controlled rectifier elements connected in a bridge configuration, with the converters being connected to a load, in a reverse-parallel configuration, so that the anode of one element is connected to the cathode of its parallel connected element, cooling fins are interposed between the planar type semiconductor controlled rectifier elements so that an individual cooling fin serves to cool directly adjacent elements disposed along the same axis in series with each other. As a result, the number of cooling fins can be sharply reduced. The converting device is especially effective for normal and reverse switching operations of a d.c. motor.

Cooling arrangement for semiconductor converter device

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Katsuta, Japan

Masahiro Tobise