Hitachi, Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Koichiro Nagata

Toshiaki Okuyama

Hiroyuki Tomita

Akihiro Nakamura

Shigetoshi Okamatsu

Yoshitaka Iwaji

Kouki Yamamoto

Yoichiro Arakawa

Toshio Katayama

Hiroshi Fujii

Shigehisa Aoyagi

Takuma Nishimura

Motomi Shimada

Shuji Soga

Koichi Miyazaki

Naohito Ikeda

Gen Tsuchida

Toshifumi Sakai

Yoshitoshi Akita

Yuusuke Arao

Haruo Nemoto

The purpose of the present invention is to provide a device monitoring technique having little restriction even on application to an already-existing device or facilitating monitoring even when a device to be monitored is in variable speed operation or under load variation. One of the representative device monitoring devices of the present invention monitors a device system using, as a power source, an AC electric motor driven by an inverter and is provided with a torque current estimation unit and a state estimation unit. The torque current estimation unit acquires information about AC currents of at least two phases and excitation current of the AC electric motor and calculates a torque current estimated value of the AC electric motor on the basis of the AC currents and the excitation current. The state estimation unit estimates the state of the device system from information including at least one of the feature amounts extracted from the torque current estimated value.

Device monitoring device and device monitoring method

Provided is a transmission device monitoring system including: a diagnostic frequency estimation unit that extracts a plurality of diagnostic frequency candidate groups from a frequency region separated by a specific frequency or more using at least current information on a motor, a gear ratio of a transmission device, and the number of stages of the transmission device, and estimates a frequency satisfying a specific relationship from frequencies obtained in the plurality of diagnostic frequency candidate groups as a diagnostic frequency; and an abnormality diagnosis unit that diagnoses abnormality of the transmission device using at least the one diagnostic frequency estimated by the diagnostic frequency estimation unit.

Transmission device monitoring system

A manufacturing systemis configured to include a driving deviceconfigured to drive a manufacturing machinein a step pertaining to product manufacture in a predetermined production management system, the driving devicedriving the manufacturing machinein the step in response to predetermined information obtained related to a state of the step.

Manufacturing system and manufacturing method

In a system for driving an electric motor by an engine generator, there is a possibility that oscillation and d-axis current are increased. In an engine generator system, a power converter () controls a generator () so that the phase of an oscillating component included in the d-axis current in the rotor magnetic flux direction of the generator () advances by 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the generator (), and further using q-axis voltage adjusting device () so that the phase of an oscillating component included in the q-axis current advances by 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the generator ().

Power conversion device

In a power conversion device that includes a PWM converting means for generating a PWM pulse by comparing three-phase voltage commands with a triangular wave carrier signal, a power converter for converting between a DC voltage and a three-phase AC voltage by driving a switching element according to the PWM pulse, a current detecting means for detecting a pulsed current flowing through a DC bus conductor of a main circuit, and a voltage command correcting means for correcting three-phase voltage commands, which corrects the three-phase voltage commands so that a line voltage value between the maximum phase and an intermediate phase and a line voltage value between the intermediate phase and the minimum phase are each equal to or larger than a predetermined value, the maximum phase, intermediate phase, and minimum phase being determined in correspondence to momentary values of the three-phase voltage commands arranged in descending order, if the voltage command is outside an allowable upper limit or lower limit, not only the voltage command for the maximum phase and/or the minimum phase but also the voltage command for the intermediate phase are corrected. Accordingly, the inability to detect a current due to a restriction imposed by an upper limit or a lower limit for an output voltage is eliminated, and highly precise control of the power conversion device is achieved independently of the situation.

Power conversion device and method for controlling thereof

An electric motor drive system having current detecting sections for detecting the currents flowing into electric motors, speed variation calculating sections for calculating the speed variation estimating values for the electric motors in accordance with the motor currents detected by the current detecting sections and the current command values for the motors corresponding to the detected currents and a speed uniformizing voltage compensating section for delivering the values that serve to compensate the amplitudes of the voltages applied to the electric motors in such a manner that the speed variation estimating values calculated by the speed variation calculating sections become equal to a predetermined value.

Electric motor drive system and electric motor control method

A slip frequency is estimated from a current instruction or detected currents in an induction motor. Acceleration impossibility in an induction motor drive unit is determined, when the slip frequency exceeds the maximum torque generating slip frequency for the predetermined interval or the time integrating result exceeds a predetermined value; when the q-axis magnetic flux exceeds the maximum torque generating q-axis magnetic flux or exceeds for a predetermined interval; when the estimated rotational speed is under a predetermined value; when the rotational speed variation rate is negative; and when the rotational speed instruction value or the estimated rotational speed is equal to or smaller than a predetermined value. An induction motor drive system and an elevating system including the induction motor drive unit are also disclosed.

Induction motor drive unit, motor drive system, and elevating system

An electric power converter apparatus having a function of converting a power source voltage into an AC voltage having an arbitrary frequency and maintaining an output voltage constant even on the power source variation, in which the electric power converter apparatus decreases the output voltage when the output voltage drops to equal to or less than a predetermined value, afterward, increases the output voltage in response to a predetermined rate of change when the power source voltage rises.

Electric power converter suppressing output voltage variation due to input voltage fluctuation

The present invention provides an induction motor controller which includes: a circuit for generating a d-axis current reference signal from a d-axis current command value and a periodically varying periodic signal; a d-axis current controller for controlling a d-axis motor current flowing through an induction motor to be controlled to match the d-axis current reference signal; parameter determining means for calculating and determining a motor parameter of the induction motor based on a deviation of the d-axis motor current from the d-axis current reference signal, and controlling a voltage applied to the induction motor using a compensation voltage calculated from the calculated and determined motor parameter, in which a control parameter for controlling the induction motor is set based on the calculated and determined motor parameter.

Induction motor controller

An object of the present invention is to provide a driver for an induction motor which performs an operation at an acceleration suitable for the magnitude of a load and is excellent in efficiency, without an acceleration failure. The driver for an induction motor includes a slip frequency estimate value arithmetic operation sectionfor arithmetically operating a slip frequency &#x3c9;s^ of an induction motorand a maximum torque generation slip arithmetic operation sectionfor arithmetically operating a slip frequency &#x3c9;smax at which a maximum torque is generated. When the slip frequency &#x3c9;s^ exceeds a predetermined value &#x3c9;smaxTH (=0.9 &#x3c9;smax, etc.) corresponding to the slip frequency &#x3c9;smax at which the maximum torque is generated, a speed change rate arithmetic operation sectionand a speed change rate correcting sectionreduce a rate of increase in a speed command &#x3c9;r*. In addition, when the slip frequency approaches the maximum torque generation slip frequency too closely, the load concerned is judged to be overloaded, and an alarm is generated.

Driver for induction motor and method of driving the same

A motor driving apparatus includes: a current instruction calculator, for calculating a current instruction value based on a deviation between a speed instruction value and an estimated speed value; a current controller, for controlling an output current based on the current instruction value; a frequency instruction calculator, for calculating a frequency instruction value based on an output voltage instruction value or an output voltage detection value, wherein, when an induction motor is to be activated, the current instruction value and the frequency instruction value are calculated directly using the speed instruction value, and an output current and an output frequency are controlled in accordance with the current instruction value and the frequency instruction value.

Driving apparatus for a motor

For use in a system in which a capacitor is connected between an AC machine and an inverter in order to improve the power factor, a controller for an AC machine capable of even when the overvoltage occurs due to the self-excitation between the AC machine and the capacitor, reactivating stably the inverter to continue the running. When the operation of the inverter is stopped and then the inverter is reactivated, the manipulation of starting the switching of the inverter is performed after a DC voltage of the inverter has been decreased to the operating voltage in the running, whereby the reactivation is performed stably without stopping the system.

Controller of AC machine

An electric motor is rotated at a velocity &ohgr; . After that, during &Dgr;t seconds, the 1st acceleration is executed at a rate (&ohgr; &minus;&ohgr; )/&Dgr;t . During this acceleration, the torque &tgr; is calculated so as to execute the time integration. After the lapse of &Dgr;t , the integrated result is stored. Next, the velocity is set to be &ohgr; . After that, during &Dgr;t seconds, the 2nd acceleration is executed at a rate (&ohgr; &minus;&ohgr; )/&Dgr;t . At the 2nd acceleration, although the integration-starting and the integration-terminating velocities are each equal to those at the 1st acceleration, the acceleration rate is modified (&ohgr; &equals;&ohgr; , &ohgr; &equals;&ohgr; , &Dgr;t &ne;&Dgr;t ). During this acceleration, the torque &tgr; is calculated so as to execute the time integration, after the lapse of &Dgr;t , storing the integrated result. The inertia J is calculated using the 1st and 2nd integrated results.

Growing community of inventors

Mito, Japan

Koichiro Nagata