Patents by Inventor Mitunori Yamashina

Mitunori Yamashina has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Controlling apparatus for induction motor
    Patent number: 5021724
    Abstract: A controlling apparatus for an induction motor for controlling the induction motor in high efficiency having a converter for supplying an electric power to the induction motor, a rotational speed detector of the induction motor, a controlling means of the converter for holding a torque of the induction motor constant while the rotational speed of the induction motor is lower than a base rotational speed and to decrease a secondary magnetic flux of the induction motor according to the rotational speed while the rotational speed of the induction motor is over the base rotational speed, and a means for varying the secondary magnetic flux according to a terminal voltage of the induction motor so as to hold the terminal voltage a predetermined constant voltage while the rotational speed of the induction motor is higher than the predetermined speed.
    Type: Grant
    Filed: November 7, 1990
    Date of Patent: June 4, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Yasuhiro Hirano, Mitunori Yamashina, Tetsuo Etoh