Patents by Inventor Yasuhiro Imazu

Yasuhiro Imazu 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: 9573489
    Abstract: Feeder sections to be a target of interchange are to be expanded in order to improve the effect of power interchange between feeders. A control device for railway power conditioner is connected to a first feeder connected to a load side of a transformer in a first railway substation including a transformer receiving power from a power grid, and a second feeder connected to a load side of a transformer in a second railway substation including a transformer receiving power from a power grid, and decides an amount of power interchanged between the first and second feeders. The control device decides the amount of power interchanged between the first and second feeders, using the received power in the first railway substation and power on the first feeder, and the received power in the second railway substation and power on the second feeder.
    Type: Grant
    Filed: November 15, 2013
    Date of Patent: February 21, 2017
    Assignees: Hitachi, Ltd., East Japan Railway Company
    Inventors: Yasuhiro Nakatsuka, Yasuhiro Imazu, Osamu Sakuchi, Masaya Ichinose, Yasuhiro Kiyofuji, Akira Bando, Jun Narushima, Toshihiko Usui, Naomi Sato, Masaki Uchita, Rikiya Inoue, Masahiko Honda
  • Patent number: 8867247
    Abstract: A commanded negative-sequence current is added to a commanded current so as to suppress double-frequency pulsation on the DC side. The commanded negative-sequence current is found from three values (i.e., the detected value of positive-sequence voltage vector on the power-supply side, the detected value of negative-sequence voltage vector, and a commanded positive-sequence current). Thus, the pulsations which occur on the DC side of a semiconductor power converter and which have a frequency double the power-supply frequency are suppressed even when the AC power supply is at fault while assuring stability of the current control system, thus permitting stable and continuous operation.
    Type: Grant
    Filed: March 15, 2012
    Date of Patent: October 21, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Akira Bando, Yasuhiro Kiyofuji, Masaya Ichinose, Hiromitsu Sakai, Yasuhiro Imazu
  • Publication number: 20140167701
    Abstract: The invention provides a power converter including a plurality of power conversion units each connected to a different feeder, a DC energy interchange unit connected to the power conversion units and connected to a secondary battery, and a power control unit which instructs the regeneration-side power conversion unit connected to the regeneration-side feeder of the feeders, through which a regenerative current flows, and the consumption-side power conversion unit connected to the consumption-side feeder through which a current consumption flows, to output power from the regeneration-side feeder to the consumption-side feeder through the DC energy interchange unit. The power control unit also determines the voltage of the DC energy interchange unit in such a manner as to input/output energy corresponding to the sum of regenerative power of the regeneration-side feeder and consumed power of the consumption-side feeder to and from the secondary battery.
    Type: Application
    Filed: December 4, 2013
    Publication date: June 19, 2014
    Applicant: Hitachi, Ltd.
    Inventors: Yasuhiro NAKATSUKA, Yasuhiro IMAZU, Akihiro MAOKA, Masaya ICHINOSE, Yasuhiro KIYOFUJI, Akira BANDO
  • Publication number: 20140152087
    Abstract: Feeder sections to be a target of interchange are to be expanded in order to improve the effect of power interchange between feeders. A control device for railway power conditioner is connected to a first feeder connected to a load side of a transformer in a first railway substation including a transformer receiving power from a power grid, and a second feeder connected to a load side of a transformer in a second railway substation including a transformer receiving power from a power grid, and decides an amount of power interchanged between the first and second feeders. The control device decides the amount of power interchanged between the first and second feeders, using the received power in the first railway substation and power on the first feeder, and the received power in the second railway substation and power on the second feeder.
    Type: Application
    Filed: November 15, 2013
    Publication date: June 5, 2014
    Applicant: Hitachi, Ltd.
    Inventors: Yasuhiro NAKATSUKA, Yasuhiro IMAZU, Osamu SAKUCHI, Masaya ICHINOSE, Yasuhiro KIYOFUJI, Akira BANDO, Jun NARUSHIMA
  • Publication number: 20120170333
    Abstract: A commanded negative-sequence current is added to a commanded current so as to suppress double-frequency pulsation on the DC side. The commanded negative-sequence current is found from three values (i.e., the detected value of positive-sequence voltage vector on the power-supply side, the detected value of negative-sequence voltage vector, and a commanded positive-sequence current). Thus, the pulsations which occur on the DC side of a semiconductor power converter and which have a frequency double the power-supply frequency are suppressed even when the AC power supply is at fault while assuring stability of the current control system, thus permitting stable and continuous operation.
    Type: Application
    Filed: March 15, 2012
    Publication date: July 5, 2012
    Applicant: Hitachi, Ltd.
    Inventors: Akira Bando, Yasuhiro Kiyofuji, Masaya Ichinose, Hiromitsu Sakai, Yasuhiro Imazu
  • Patent number: 7485980
    Abstract: An excitation power converter of a doubly-fed generator is protected from excess current to be caused by ground fault or system disturbance and operation continuity of the power converter is ensured. In a power converter system, in order not to flow excess current generated in secondary windings of the doubly-fed generator into the power converter, a rectifier is connected in parallel to the power converter via a reactor, a DC link of the rectifier is connected to a DC link of the power converter, excess current flowing from the secondary windings is separately flowed at a reactor impedance ratio to reduce an amount of current flowing into the power converter, and a semiconductor switching element of an excess current generation arm of the power converter is set to an on-state.
    Type: Grant
    Filed: January 18, 2007
    Date of Patent: February 3, 2009
    Assignee: Hitachi, Ltd.
    Inventors: Masaya Ichinose, Shinya Oohara, Motoo Futami, Yasuhiro Imazu
  • Publication number: 20070210651
    Abstract: An excitation power converter of a doubly-fed generator is protected from excess current to be caused by ground fault or system disturbance and operation continuity of the power converter is ensured. In a power converter system, in order not to flow excess current generated in secondary windings of the doubly-fed generator into the power converter, a rectifier is connected in parallel to the power converter via a reactor, a DC link of the rectifier is connected to a DC link of the power converter, excess current flowing from the secondary windings is separately flowed at a reactor impedance ratio to reduce an amount of current flowing into the power converter, and a semiconductor switching element of an excess current generation arm of the power converter is set to an on-state.
    Type: Application
    Filed: January 18, 2007
    Publication date: September 13, 2007
    Inventors: Masaya Ichinose, Shinya Oohara, Motoo Futami, Yasuhiro Imazu
  • Patent number: 7145262
    Abstract: A wind turbine generator system is equipped with a three phase generator connected to a shaft of a windmill, a converter connected to a stator of the generator, and an inverter connected to the converter and also to an electric power system. The system extracts a torsional vibration component of the shafting between the windmill and generator from the detected rotation speed of the generator, regulates the active component of the current command to the converter according to the vibration component, and controls so as to minimize the rotation speed variation of the generator.
    Type: Grant
    Filed: June 2, 2006
    Date of Patent: December 5, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Akira Kikuchi, Motoo Futami, Yasuhiro Imazu, Yoshio Eguchi
  • Publication number: 20060214429
    Abstract: A wind turbine generator system is equipped with a three phase generator connected to a shaft of a windmill, a converter connected to a stator of the generator, and an inverter connected to the converter and also to an electric power system. The system extracts a torsional vibration component of the shafting between the windmill and generator from the detected rotation speed of the generator, regulates the active component of the current command to the converter according to the vibration component, and controls so as to minimize the rotation speed variation of the generator.
    Type: Application
    Filed: June 2, 2006
    Publication date: September 28, 2006
    Inventors: Akira Kikuchi, Motoo Futami, Yasuhiro Imazu, Yoshio Eguchi
  • Patent number: 7095132
    Abstract: An object of the present invention is to minimize the torsional vibration caused on the shafting of the wind turbine genarator system so as to operate the windmill stably. A wind turbine genarator system according to the present invention, equipped with a synchronous generator connected to the shaft of a windmill, converter connected to the stator of the synchronous generator, and inverter connected to the converter and also to an electric power system, extracts the torsional vibration component of the shafting between the windmill and synchronous generator from the detected rotation speed of the synchronous generator, regulates the active component of the current command to the converter according to the vibration component, and controls so as to minimize the rotation speed variation of the synchronous generator.
    Type: Grant
    Filed: July 20, 2004
    Date of Patent: August 22, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Akira Kikuchi, Motoo Futami, Yasuhiro Imazu, Yoshio Eguchi
  • Publication number: 20050017512
    Abstract: An object of the present invention is to minimize the torsional vibration caused on the shafting of the wind turbine genarator system so as to operate the windmill stably. A wind turbine genarator system according to the present invention, equipped with a synchronous generator connected to the shaft of a windmill, converter connected to the stator of the synchronous generator, and inverter connected to the converter and also to an electric power system, extracts the torsional vibration component of the shafting between the windmill and synchronous generator from the detected rotation speed of the synchronous generator, regulates the active component of the current command to the converter according to the vibration component, and controls so as to minimize the rotation speed variation of the synchronous generator.
    Type: Application
    Filed: July 20, 2004
    Publication date: January 27, 2005
    Inventors: Akira Kikuchi, Motoo Futami, Yasuhiro Imazu, Yoshio Eguchi