Patents by Inventor Tadashi Takaoka

Tadashi Takaoka 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).

  • Patent number: 5248926
    Abstract: A control apparatus for an electric rolling stock makes it possible to use a single associated train in a variety of transit services including an express transit service to an accommodation train service. The apparatus comprises an induction motor controlled by an inverter. For an express transit operation (over a long inter-station distance), the ratio of output voltage and the frequency of the inverter is decreased to thereby increase a command current in a variable voltage/variable frequency region. For the accommodation train operation (over short inter-station distance), a control pattern reverse to the above is adopted. The electric rolling stock can adapt itself to the running conditions. Besides, the problem of overheating of the induction motor can be solved successfuly.
    Type: Grant
    Filed: April 17, 1991
    Date of Patent: September 28, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyoshi Kotake, Takeshi Kawazoe, Tadashi Takaoka
  • Patent number: 4825131
    Abstract: A DC voltage on an electric car stringing is supplied to a variable voltage and variable frequency PWM inverter so as to be converted into a three-phase alternating current which is supplied to a plurality of three-phase induction motors. The motors are connected to different wheels to drive an electric car. The inverter is controlled on the basis of an operating frequency command determined by adding or subtracting a slip frequency command to or from a motor speed and a voltage command proportional to the operating frequency command. On the other hand, a motor current command is set and compared with a maximum current value of currents of the plurality of motors, and the slip frequency command is corrected in accordance with a difference therebetween.
    Type: Grant
    Filed: October 30, 1987
    Date of Patent: April 25, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Yoshio Nozaki, Shigetoshi Okamatsu, Tadashi Takaoka
  • Patent number: 4752723
    Abstract: A chopper control system for a vehicle driven by a shunt motor. The system is provided with an integrating circuit for generating a command value for the voltage which is to be supplied to an armature of the motor in accordance with the difference between the command value of current which is to be supplied to the armature and the detected value of current flowing through the armature, and with a voltage control circuit for generating a control signal the value of which is proportional to the above command voltage value and is inversely proportional to the power source voltage value. The gate of a chopper switch is on-off controlled by the above control signal, so that the power source voltage value is converted into a voltage value corresponding to the command voltage value and is then supplied to the armature of the motor.
    Type: Grant
    Filed: February 17, 1987
    Date of Patent: June 21, 1988
    Assignee: Hitachi, Ltd.
    Inventors: Makoto Nohmi, Tadashi Takaoka, Eiji Kozu
  • Patent number: 4684859
    Abstract: A novel control system for the motor or the like is disclosed which operates basically on principle that the power flowing in during the conduction of a chopper gate of a chopper device is integrated, and when the integrated value reaches a target, the gate is turned off, thereby realizing the control of an instantaneous value and high response and stability without the conventional feedback control. The target value is also reduced against the excess of the source voltage under variations in load for the regenerated power. Further, a constant-voltage control limiter is added to improve the ability to prevent a slip and race.
    Type: Grant
    Filed: January 17, 1985
    Date of Patent: August 4, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Makoto Nohmi, Shoji Miyamoto, Tadashi Takaoka, Hiroyasu Oshima
  • Patent number: 4093162
    Abstract: A train operation control apparatus includes a memory for prestoring speed instructions in accordance with the travelled distances of a train and a counter which starts to operate upon train's passing through a predetermined point to count input signals representative of a travel speed of the train. A speed instruction is read out of the memory in response to a content of the counter so that the train follows the speed instruction. Before the operation of the counter is started, a maximum count of the counter is preset so that a minimum speed instruction is read out of the memory at the start of operation, and based on the content thereof a fault of the counter is detected so that a brake instruction is issued to the train.
    Type: Grant
    Filed: February 15, 1977
    Date of Patent: June 6, 1978
    Assignee: Hitachi, Ltd.
    Inventors: Tadashi Takaoka, Eiichi Toyota