Hitachi, Ltd.

The Kansai Electric Power Co., Inc.

Yoji Tanaka

Toshiaki Okuyama

Akira Bando

Noriyoshi Takahashi

Hiroto Nakagawa

Masatoshi Watanabe

Eiji Haraguchi

Kenichi Ono

Hiroshi Sugisaka

Hiroshi Kashiwazaki

Yukio Kitabayashi

An induction generator/motor system has an induction machine connected at its secondary side to a cyclo-converter. An induced voltage develops when the cyclo-converter pauses during a transient phenomenon occurring in the system. When the induced voltage exceeds a predetermined voltage range which covers the maximum output voltage derivable from the cyclo-converter, the polarity of thyristor converters of the cyclo-converter is switched such that the induced voltage is applied to a thyristor converter to be rendered conductive next in forward relationship therewith, thereby preventing occurrence of an overvoltage.

Induction generator/motor system

A variable speed rotary electric machine comprises a stator composed of a stator core and first and second stator windings wound on the stator core, and a cage rotor mounted rotatably within the stator and composed of a rotor core and rotor conductor disposed in a squirrel-cage configuration. The first stator winding is connected to an AC power supply of a fixed frequency. The second stator winding is connected to a power supply of a variable frequency. The first and second stator windings are so wound as to form, respectively, numbers of poles differing from each other. The rotor conductors of the cage rotor are electromagnetically coupled with the magnetic flux generated by the first and second stator windings, respectively, and so disposed as to form a number of poles which is intermediate between the number of the poles formed by the first stator winding and the number of poles formed by said second stator winding.

Variable speed rotary electric machine

Growing community of inventors

Hitachi, Japan

Yoji Tanaka