Hitachi, Ltd.

Kazuki Tani

Katsuya Oda

Yoshinobu Kimura

Shinichi Saito

Takashi Ogawa

Hiroshi Suzuki

Yoshitaka Sasago

Akio Shima

Daisuke Ryuzaki

Junichi Sakano

Hideo Arimoto

Misuzu Sagawa

Etsuko Nomoto

Tadashi Okumura

Kumiko Konishi

Takashi Takahama

Ryuusei Fujita

A temperature abnormality of the power module is accurately detected. A power conversion device including a power semiconductor module with a switching element, includes: a gate driver circuit configured to drive a switching element and transmitting a response signal upon a switching operation of the switching element; a control unit device configured to output to a gate driver circuit an instruction signal for switching; a temperature detection unit configured to calculate a bonding temperature of the switching element based on a response signal to the instruction signal; and a calculation unit configured to determine a state of a power semiconductor module according to a bonding temperature calculated by the temperature detection unit and the response signal.

Power conversion device, motor control system, and diagnosis method for power conversion device

A power converter is provided with a power semiconductor module having a switching element. The power converter includes a gate drive circuit, a first detection unit, a second detection unit, a time measuring unit, and an abnormality diagnostic unit. The gate drive circuit drives the switching element and outputs a feedback signal based on a switching operation of the switching element. The first detection unit detects a change in a feedback signal of an upper arm of the power converter. The second detection unit detects a change in a feedback signal of a lower arm of the power converter. The time measuring unit measures a difference between detection timings of a signal change by the first detection unit and a signal change by the second detection unit. The abnormality diagnostic unit performs diagnosis of the power converter based on a measurement result by the time measuring unit.

Power converter and diagnostic system thereof

Provided is a silicon carbide semiconductor device in which SiC-MOSFETs are formed within an active region of an n-type silicon carbide semiconductor substrate, and a p-type semiconductor region is formed on an upper surface of an epitaxial layer so as to surround the active region.

Silicon carbide semiconductor device, power module, and power conversion device

In an optical modulatorof an embodiment, an optical waveguide coreis configured from an ntype semiconductor region, a gate insulating filmon the ntype semiconductor region, and a ptype semiconductor regionon the gate insulating film. Further, a width Wof the ntype semiconductor regionand a width Wof the ptype semiconductor regionare equally formed and are layered without being shifted. Therefore, an optical modulator having stable optical characteristics can be provided.

Optical modulator and method for manufacturing same

In order to provide a highly reliable silicon-germanium semiconductor optical element of high luminous efficiency or of low power consumption that can reduce or prevent the occurrence of dislocations or crystal defects on the interface between a light emitting layer or a light absorption layer and a cladding layer, in a silicon-germanium semiconductor optical element, a germanium protective layerof non-light emission is disposed between a germanium light emitting layer or the light absorption layerand a cladding layerdisposed above a substrate. The germanium protective layerhas the electrical conductivity different from electrical conductivity of the germanium light emitting layer or the light absorption layer

Semiconductor optical element

The light emitting device includes an active layer formed on a semiconductor substrate for emitting light, a semiconductor layer of a first conductivity type electrically connected to one end of the active layer, a semiconductor layer of a second conductivity type electrically connected to the other end of the active layer, first and second electrodes, a feedback mechanism for laser oscillation, and a waveguide for guiding the light emitted from the active layer, in which the active layer is made of a semiconductor having an affinity with a silicon CMOS process, and the semiconductor layer of the first conductivity type and the semiconductor layer of the second conductivity type, and the waveguide are each made of silicon as a part of the semiconductor substrate.

Light emitting device, manufacturing method thereof, and optical transceiver

To provide a light-emitting element where electrons are efficiently injected into a Ge light emission layer and light can be efficiently emitted, the light-emitting element has a barrier layerwhich is formed on an insulating film, worked in a size in which quantum confinement effect manifests and made of monocrystalline Si, a p-type diffused layer electrodeand an n-type diffused layer electroderespectively provided at both ends of the barrier layer, and a monocrystalline Ge light emission partprovided on the barrier layerbetween the electrodes. At least a part of current that flows between the electrodesflows in the barrier layerin a horizontal direction with respect to a substrate

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Tokyo, Japan

Kazuki Tani