Other

Nippon Steel Corporation

Tokyo Institute of Technology

Tadayuki Kitahara

Ryuichi Shimada

Kazuhiko Fukutani

Takanori Isobe

Yoshiaki Nakamura

Kazuto Yamamoto

Kenji Umetsu

Takashi Miyakawa

Hideo Narisawa

In an induction motor group control system, magnetic energy recovery switches () are connected in series to an induction motor () directly driven by a commercial power supply, and a plurality of induction motor control devices () enabling voltage control and reactive power control of the induction motorare employed to control generation of reactive power so as to maximize a power factor of the entire plurality of AC loads including the induction motor or compensate variations in voltage of an AC power supply ().

Induction motor control device and induction motor group control system

This invention provides a steel pipe material weld zone heating method and apparatus for melting and welding the weld zone of a steel pipe material that during continuous induction heating and welding of moving steel pipe material as the material being heated controls temperature distribution and molten steel shape and weld frequency fluctuation with high accuracy and high efficiency, irrespective of the shape of the heated region of material being heated or the material properties of the material being heated, which comprises a first imaging device, a weld zone temperature distribution computation device, a heating control device, and a variable frequency alternating current power supply device.

Steel pipe material weld zone heating apparatus and method

Reverse conducting type semiconductor switches are arranged in a bride from, an energy storage capacitor is connected with its DC terminal to obtain a magnetic energy regeneration switch, and then an induction coil is connected to its AC terminal. An AC pulse current of variable frequency is obtained by applying a gate signal to the semiconductor switch to thereby turn it ON/OFF; since a voltage is generated automatically by regenerating magnetic energy, a DC power supply is connected to the opposite ends of the capacitor through a smoothing coil, thus injecting power.

Electric power unit for induction heating

Growing community of inventors

Tokyo, Japan

Tadayuki Kitahara