Mitsubishi Electric Corporation

Ryota Onishi

Toshiyuki Fujii

Shigeo Hayashi

Ryoji Miyatake

Akiko Tabuchi

Shinya Noguchi

A multilevel converter includes a first arm connected between a positive voltage terminal and an alternating-current terminal and a second arm connected between the alternating-current terminal and a negative voltage terminal. Each of the first and second arms includes a plurality of cascaded unit cells. Each unit cell has a capacitor charged to a direct-current voltage and outputs a voltage across terminals of the capacitor or 0 V. The plurality of unit cells as being helically cascaded implement a reactor.

AC-DC power conversion device including helically cascaded unit cells

Each phase arm of a power conversion device includes at least one converter cell connected in series. For each converter cell, an element driving unit is provided which turns on one switching element in the converter cell as a startup element. The element driving unit is supplied with power from a DC capacitor, and when voltage of the DC capacitor exceeds startup voltage Vsh, turns on the startup element. Thus, at the time of startup of the power conversion device, the DC capacitor in each converter cell is initially charged to desired voltage.

Power conversion device

A power generation system is provided in which, when a static frequency converter (SFC) is connected to synchronous generator's armature windings, an AC exciter performs AC excitation by allowing a d-axis winding and a q-axis winding of the AC exciter to configure d-q orthogonal axes; and, at the time of steady-state operation of the synchronous generator, an alternating current(s) supplied from an electric power source is rectified by a thyristor excitation device, and also the AC exciter thereby performs DC excitation by connecting the d-axis winding and the q-axis winding in series with each other.

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Tokyo, Japan

Ryota Onishi