Kabushiki Kaisha Yaskawa Denki

Kazuhiro Nonaka

Yoichi Yamamoto

Hideaki Iura

Mitsujiro Sawamura

Satoshi Sueshima

Katsushi Terazono

Masaki Nakai

Yuichi Terazono

An inverter controller comprising an AC motor as a load. A rectifying circuit converts AC power from an AC power source into DC power. A smoothing capacitor smoothens a DC voltage from the rectifying circuit. An inverter circuit converts DC power supplied via the smoothing capacitor into a desired frequency. A current detection circuit detects a output current of the inverter circuit. A voltage detection circuit detects a terminal voltage (Vpn) of the smoothing capacitor. A voltage command calculation circuit calculates a voltage command to the AC motor. A speed command calculation circuit calculates a speed command to be used when it is determined that the AC power source is in a power failure state or when the terminal voltage (Vpn) reaches a certain value.

Inverter controller and method for operating the same

It is the objective of the present invention to provide a sensorless vector control method and a control apparatus, for an alternating-current motor, that can smoothly restart an alternating-current motor in the free running state. According to the present invention, when a current that flows in an alternating-current motor () at a restart timethe alternating-current motor () continuously flows at a designated current level or higher for a designated period of time, it is determined that the rotational direction or the velocity of the alternating-current motor () is incorrectly estimated, and a direct current or a direct-current voltage is again applied to again estimate the rotational direction and the velocity.

Sensorless vector control method for alternating-current motor and control apparatus therefor

Growing community of inventors

Kitakyushu, Japan

Kazuhiro Nonaka