Hitachi, Ltd.

Hitachi Mito Engineering Co., Ltd.

Tetsu Sugiura

Kiyoshi Nakata

Tetsuo Kojima

Takeshi Shinomiya

Masafumi Makino

Masahiro Nagasu

Motomi Shimada

Yasushi Nakamura

Yuichiro Nozaki

Masaomi Konishide

Yasuhiko Kono

Ryoichi Oishi

Tadanori Sato

Toshio Sekine

Takehiro Kawamoto

Kazufumi Muraoka

Masataka Ayata

A DC power supply including a resonant circuit on a secondary side of a transformer suppresses a surge voltage during power recovery of diodes constituting a rectifier circuit, correctly estimates a load current from a secondary current of the transformer, and adjusts supplied power when a load is light. The DC power supply includes a DC voltage source, a converter, a transformer, a rectifier circuit, a resonant circuit composed of a resonant switch and a resonant capacitor, a filter reactor, a filter capacitor, a snubber diode, a snubber capacitor, a load, first and second voltage sensors, a current sensor, and a controller for controlling gate pulses of semiconductor devices constituting a converter and the resonant switch and a signal for adjusting operation timings of A/D converters converting the signals of these sensors.

DC power supply including resonant circuit for reducing switching losses

A power converter includes a first electric power conversion unit having an inverter for converting a first DC electric power to an AC electric power, an AC circuit connected to the first electric power conversion means;

Power converter and power converter of rolling stock

Semiconductor element groups constituting a unit are mounted on a cooler heat receiving parton the same plane and are adapted to radiate heat by self-cooling or cooling by wind. First and fourth semiconductor elements Q, Qare arranged on the lower side of the cooler heat receiving part, second and third semiconductor elements Q, Qare arranged in the middle, a first diode Dand a second diode Dare arranged on the upper side, the first and second semiconductor elements Q, Q, as well as the third and fourth semiconductor elements Q, Qare each arranged in positions opposite to each other in a horizontal direction with respect to a centerline of a cooler in a vertical direction.

Electric power conversion device

Growing community of inventors

Hitachinaka, Japan

Tetsu Sugiura