Hitachi, Ltd.

Hitachi Construction Machinery Co., Ltd.

Masataka Sasaki

Katsumi Ishikawa

Koichi Suda

Ryuichi Saito

Hideki Miyazaki

Kinya Nakatsu

Hidetoshi Satake

Toshiyuki Ajima

Katsuaki Takahashi

Satoshi Ibori

Masahiro Sano

Yoshihiro Uchino

Masato Takase

Shiho Izumi

Koichiro Adachi

Manabu Edamura

Kazuji Yamada

Hiroyuki Saito

Seiji Ishida

Kazuhiro Suzuki

Kazuo Fujishima

Tokihito Suwa

Yasuaki Aoyama

Yusuke Kajita

Akihiro Tamba

Makoto Hirose

Hajime Urai

Keiji Maekawa

Tatsuya Shigemura

Katsuhiko Shiraishi

Yoichi Oshita

Hisashi Urasaki

Yukio Sonobe

Ruichi Saito

Bunji Furuyama

A hybrid or battery type working machine including a hydraulic pump, an electric motor, an electric storage device, and a control device which controls a pump absorption horsepower maximum value in accordance with an amount of electricity stored in the electric storage device. The control device reduces the pump absorption horsepower maximum value by dividing the pump absorption horsepower maximum value into a plurality of regions having different target flow rates, and reduces the pump absorption horsepower maximum value from an old pump absorption horsepower maximum value corresponding to the pump absorption horsepower maximum value which has not yet been reduced to a new pump absorption horsepower maximum value corresponding to the pump absorption horsepower maximum value which has been reduced, so that temporal differences among the regions can increase in a descending order of a target flow rate.

Operating machine

A method for controlling a power switching apparatus to solve problems including: setting a target time reaching a predetermined position immediately before a target phase by a time calculator during an opening and closing operation of a movable arc contact with respect to a fixed arc contact in a target phase at a predetermined average switching speed; and controlling an electric motor at a speed equal to or less than an average switching speed immediately before the target phase from an operation start time to the target time by a motor controller.

Method for controlling power switching apparatus

The invention provides a switchgear that is capable of increasing a degree of freedom of a position of a moving arcing contact in a circuit breaker, does not require dimension management of components and a mechanism for adjusting a position of the moving arcing contact, and is capable of simplifying fabrication of components and assembly of devices and reducing cost. The switchgear according to the invention includes: a circuit breaker that is configured of a fixed arcing contact installed at a fixed-side conductor and a moving arcing contact installed at a moving electrode that opens and closes with respect to the fixed arcing contact; a linear motor that generates drive force for operating the moving arcing contact; a position detecting device that detects a position of a moving element of the linear motor; a contact detecting device that detects a contact state between the fixed arcing contact and the moving arcing contact; and a control device that sets a moving range of the moving arcing contact by controlling a voltage and a phase to be supplied to the linear motor based on the contact state between the fixed arcing contact and the moving arcing contact, which is detected by the contact detecting device, and position information of the moving element of the linear motor, which is detected by the position detecting device.

Switchgear

Construction machine capable of incorporating an engine and using an external power source. The construction machine includes an electrical storage device performing a charge with the external power source, uses the electrical storage device to provide assist when the power of the engine is insufficient, uses an electrical charge in the electrical storage device systematically in accordance with work time, and efficiently uses the electrical storage device by controlling its discharge amount in accordance with load status. The construction machine includes the engine, accessory loads connected to the engine, an assist electric motor driven by the engine, electrical power converters for converting an AC current, which is the output current of the assist electric motor, to a DC current, and the electrical storage device connected to the DC side of each electrical power converter. The electrical storage device becomes charged through a charging device from the external power source.

Construction machine

An inverter system having a semiconductor device, and a railway vehicle using this inverter, provide a more accurate determination of whether an abnormal heat generation from the inverter is associated with an error of the inverter system or is due to other causes, by use of a plurality of temperature detecting elements at a plurality of sites associated with the semiconductor device. An error detection section applies inputs from the temperature detecting elements, captures a trend of the differential value based on the plurality of temperature inputs using period sampling wherein an error associated with the semiconductor device, and not from some other condition such as outside environment temperature, is determined based on differences from, or a change in, the initial trend.

Inverter system and vehicle

A drive circuit that controls a switching device ON/OFF and a soft cutoff command circuit that gradually decreases the gate terminal voltage of the switching device when short circuit of the switching device is detected. Additionally, an ON-pulse retention command circuit retains the output of the drive circuit ON when the gate terminal voltage is judged to have exceeded a specified value by a gate voltage judgment comparator that detects the gate terminal voltage of the switching device.

Drive circuit for switching device

A position detecting device which can increase accuracy in detecting the pole position of a motor used to perform quick acceleration and deceleration over the range from a zero speed to a high rotation speed, and a synchronous motor driving device using the position detecting device. A position detector detects basic-wave component signals in sensor signals and executes position calculation. A correcting unit calculates signal information representing at least one of a gain, an offset and a phase by a phase detector from the basic-wave component signals detected by an error calculator, and makes correction based on the calculated signal information such that a position detection error is zero.

Position detecting device and synchronous motor driving device using the same

A collector voltage of a power management semiconductor device is detected by a first comparator, and when the detected collector voltage exceeds a first reference voltage, the first comparator outputs a first detection signal. Furthermore, a gate voltage of the power management semiconductor device is detected by a second comparator, and when the detected gate voltage exceeds a second reference voltage, the second comparator outputs a second detection signal. The second reference voltage is a minimum gate voltage for feeding a rated power to the power management semiconductor device or over, and less than a line power voltage of a drive circuit of the power management semiconductor device. When both the first detection signal and second detection signal are being outputted, the gate voltage is reduced by a gate voltage reduction means so as to protect the power management semiconductor device from overcurrent and overvoltage.

Protection circuit for power management semiconductor devices and power converter having the protection circuit

In an inverter maintenance system, while an inverter of a user, a user support server of maker, and also, a portable telephone capable of accessing to a Web server are employed, such information required to maintain/manage the inverter is transferred/received by way of the portable telephone. Thus, various sorts of requests can be accepted by both the user support server and the Web server.

Inverter maintenance system and inverter

In such a product that torque of a motor is continuously generated when a rotation number of the motor is nearly equal to zero, since an output voltage is kept at a constant value in accordance with a rotation position of the motor, such a condition that currents are concentrated in a specific element are maintained. As a result, a temperature of the specific element is increased, so that there are problems that a temperature fail of an inverter apparatus may readily occur, and thus, lifetimes of elements are lowered. In a power converter of a motor drive apparatus, windings are energizing-controlled in such a manner that only 1 phase of a switching circuit is pulse-width-controlled when the motor is under motor locking condition.

Motor drive apparatus and method and electrically driven brake apparatus

A drive circuitthat controls a switching deviceON/OFF and a soft cutoff command circuit that gradually decreases the gate terminal voltage of the switching devicewhen short circuit of the switching deviceis detected. Additionally, an ON-pulse retention command circuitretains the output of the drive circuitON when the gate terminal voltage is judged to have exceeded a specified value by a gate voltage judgment comparatorthat detects the gate terminal voltage of the switching device

A power converter includes a shunt resistor constituted by a shunt resistance and a plurality of main electrodes made of a sheet-like resistive material. In the shunt resistor, plates lower in volume electric resistivity than the resistive material, higher in thermal conductivity than the resistive material and thicker in thickness than the resistive material are fixedly attached by solder, to the side surfaces of the main electrodes opposite to the side surfaces with which the main electrodes are fixedly attached to an insulating layer. At least one plate main electrode for electrically connecting with main circuit wiring is provided in each of the plates. At least one constricted portion is formed between each of the plate main electrodes and the shunt resistance. Plate detection electrodes for detecting a voltage between the opposite ends of the shunt resistance is provided on the plates near the shunt resistance portion.

Power converter with shunt resistor

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Hitachi, Japan

Masataka Sasaki