Hitachi, Ltd.

Nec Corporation

Makoto Kadowaki

Hiroyuki Fujita

Shuji Katoh

Yasuhiro Kiyofuji

Shigenori Inoue

Hideki Ogata

Kunimitsu Kurita

A power conversion apparatus including a three-phase transformer having at least four three-phase windings, and three converter arms each configured by connecting one or plural unit converters each including a switching device and an energy storage element in series. A power source or a load is connected to a first three-phase winding of the transformer, three series circuits which connects second and third three-phase windings of the transformer, and the converter arms in series with each other are connected in parallel, the parallel connection point is a DC terminal, and a magnitude relationship between a coupling coefficient of the first and second three-phase windings, and a coupling coefficient of the first three- and third three-phase windings is equal to a magnitude relationship between a coupling coefficient of the fourth and second three-phase windings, and a coupling coefficient of the fourth and the third three-phase windings.

Power conversion apparatus and high-voltage DC transmission system

In receiving an optical digital burst signal in an optical communication system, an optical digital burst signal is converted into an electric digital burst signal. A threshold level is determined from the electric digital burst signal. Based on a threshold signal having the determined threshold level whether each of bits of the electric digital burst signal is in a high level or a low level is identified by an identifying circuit. When a sync pattern is detected from the electric digital burst signal, a hunting signal is generated by a synchronization detecting circuit. The duration time of the threshold signal is selected as one of short and long duration times based on whether the hunting signal is significant or insignificant.

Burst signal receiving apparatus with different holding times of

Growing community of inventors

Tokyo, Japan

Makoto Kadowaki