Patents by Inventor Takeshi Wakatabe

Takeshi Wakatabe 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).

  • Refrigerator
    Patent number: 6367273
    Abstract: A refrigerator, having a motor for driving a compressor, an inverter for controlling the operation of the motor, a converter responsive to AC to perform a boosting function to supply DC of variable voltage to the inverter, converter control means for controlling the converter so that a plurality of DC voltages are outputted thereby and inverter control means for controlling the inverter in pulse width modulation each of the plurality of voltages. The lowest voltage among the plurality of voltages being a voltage which turns off the boosting function of the converter.
    Type: Grant
    Filed: April 13, 2001
    Date of Patent: April 9, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Junichi Takagi, Makoto Ishii, Noriaki Arakawa, Takeshi Wakatabe, Hideki Yoshida, Hideyuki Nakamura, Hideo Kumakura
  • Refrigerator
    Publication number: 20010035018
    Abstract: A refrigerator, having a motor for driving a compressor, an inverter for controlling the operation of the motor, a converter responsive to AC to perform a boosting function to supply DC of variable voltage to the inverter, converter control means for controlling the converter so that a plurality of DC voltages are outputted thereby and inverter control means for controlling the inverter in pulse width modulation each of the plurality of voltages. The lowest voltage among the plurality of voltages being a voltage which turns off the boosting function of the converter.
    Type: Application
    Filed: April 13, 2001
    Publication date: November 1, 2001
    Inventors: Junichi Takagi, Makoto Ishii, Noriaki Arakawa, Takeshi Wakatabe, Hideki Yoshida, Hideyuki Nakamura, Hideo Kumakura
  • Refrigerator
    Patent number: 6244061
    Abstract: When inverter control is implemented in a refrigerator or the like, the rotating speed of a compressor motor is often operated at the preset minimum rotating speed. At this time, there has been a problem that when the DC voltage is boosted, the efficiency of the circuit drops due to switching loss in the power element. Still more, when the DC voltage is boosted even at the minimum rotating speed, the lowest voltage of the DC voltage must be controlled at 163 V or more including the fluctuation of the voltage. Therefore, there has been a problem in that the efficiency of the compressor motor also drops.
    Type: Grant
    Filed: June 18, 1999
    Date of Patent: June 12, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Junichi Takagi, Makoto Ishii, Noriaki Arakawa, Takeshi Wakatabe, Hideki Yoshida, Hideyuki Nakamura, Hideo Kumakura