Patents by Inventor Miwako TANAKA

Miwako TANAKA 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: 11309807
    Abstract: A power conversion device includes: a power converter circuit which converts a direct-current power, output from a decentralized power supply, into an alternating-current power, and outputs the alternating-current power to a power distribution grid; a voltage target value generation unit which removes a high-frequency variation from a root mean square of a voltage detected by a voltage detection unit to generate a voltage target value; a correction unit which corrects the voltage target value when the correction unit detects that the automatic voltage regulator has performed an action; and a command unit which, if the voltage at the point of interconnection detected by the voltage detection unit deviates from a voltage control deadband referenced to the voltage target value, commands the power converter circuit to output a reactive power based on a magnitude of the deviated amount of voltage.
    Type: Grant
    Filed: January 11, 2019
    Date of Patent: April 19, 2022
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Miwako Tanaka, Hiroki Ishihara
  • Patent number: 11239664
    Abstract: An AC/DC converter and a DC/DC converter are disposed corresponding to a power generator. The AC/DC converter converts AC power generated by the power generator into a generated voltage, and outputs the generated voltage to a power line. The DC/DC converter converts the generated voltage on the power line into a collection voltage, and outputs the collection voltage to a collection line. DC power in a DC voltage grid formed of the collection line is transmitted through a DC/AC converter to an AC power grid. When a short-circuit fault occurs in the DC power grid or the AC power grid, a control command value for the AC/DC converter or the DC/DC converter is adjusted so as to suppress incoming electric power flowing from the power generator in accordance with fluctuations of a collection voltage.
    Type: Grant
    Filed: January 24, 2019
    Date of Patent: February 1, 2022
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Miwako Tanaka, Toshiyuki Fujii
  • Publication number: 20220014116
    Abstract: A power conversion device includes: a power converter circuit which converts a direct-current power, output from a decentralized power supply, into an alternating-current power, and outputs the alternating-current power to a power distribution grid; a voltage target value generation unit which removes a high-frequency variation from a root mean square of a voltage detected by a voltage detection unit to generate a voltage target value; a correction unit which corrects the voltage target value when the correction unit detects that the automatic voltage regulator has performed an action; and a command unit which, if the voltage at the point of interconnection detected by the voltage detection unit deviates from a voltage control deadband referenced to the voltage target value, commands the power converter circuit to output a reactive power based on a magnitude of the deviated amount of voltage.
    Type: Application
    Filed: January 11, 2019
    Publication date: January 13, 2022
    Applicant: Mitsubishi Electric Corporation
    Inventors: Miwako TANAKA, Hiroki ISHIHARA
  • Publication number: 20210391721
    Abstract: A management apparatus periodically transmits information for setting a first voltage range and a second voltage range smaller than the first voltage range to a distribution power supply apparatus. The distribution power supply apparatus removes, from an interconnection point voltage at an interconnection point with the distribution system, a voltage fluctuation component with a cycle shorter than a cycle in which the information is transmitted from the management apparatus to thereby generate a voltage command value of the interconnection point, and performs reactive power control for eliminating a voltage deviation of the interconnection point voltage with respect to the voltage command value. In the reactive power control, the generation of the reactive power is started when an absolute value of the voltage deviation exceeds the first voltage range, and the reactive power is adjusted until the absolute value falls below the second voltage range.
    Type: Application
    Filed: December 10, 2018
    Publication date: December 16, 2021
    Applicant: Mitsubishi Electric Corporation
    Inventors: Hiroki ISHIHARA, Miwako TANAKA
  • Patent number: 10958068
    Abstract: A DC transmission system transmits AC power generated by a generator to an AC distribution grid and a DC distribution grid using DC power. The DC transmission system includes an AC/DC converter, a DC/DC converter, and a DC/AC converter. The AC/DC converter outputs DC power by converting AC power from the generator. The DC/DC converter boosts a first voltage of the DC power outputted from the AC/DC converter, into a second voltage. The DC/AC converter outputs, to the AC distribution grid, AC power by converting the DC power outputted from the DC/DC converter. When the second voltage changes, the DC/DC converter controls the first voltage in response to the change in the second voltage.
    Type: Grant
    Filed: September 7, 2017
    Date of Patent: March 23, 2021
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Miwako Tanaka, Toshiyuki Fujii
  • Publication number: 20200395758
    Abstract: An AC/DC converter and a DC/DC converter are disposed corresponding to a power generator. The AC/DC converter converts AC power generated by the power generator into a generated voltage, and outputs the generated voltage to a power line. The DC/DC converter converts the generated voltage on the power line into a collection voltage, and outputs the collection voltage to a collection line. DC power in a DC voltage grid formed of the collection line is transmitted through a DC/AC converter to an AC power grid. When a short-circuit fault occurs in the DC power grid or the AC power grid a control command value for the AC/DC converter or the DC/DC converter is adjusted so as to suppress incoming electric power flowing from the power generator in accordance with fluctuations of a collection voltage.
    Type: Application
    Filed: January 24, 2019
    Publication date: December 17, 2020
    Applicant: Mitsubishi Electric Corporation
    Inventors: Miwako TANAKA, Toshiyuki FUJII
  • Publication number: 20200373836
    Abstract: A subtracting unit calculates a voltage deviation of an output voltage of a DC-to-DC converter from a target voltage. A feedback control variable calculator calculates a feedback control variable in each control cycle. In a control cycle in which a crossing of the output voltage and the target voltage is detected by a feedforward control determination unit, a feedforward control variable calculator calculates a feedforward control variable so that a change in the output voltage is prevented. A switching control signal generator generates a control signal for the DC-to-DC converter for controlling the output voltage, according to a summation of the feedforward control variable and the feedback control variable.
    Type: Application
    Filed: December 5, 2018
    Publication date: November 26, 2020
    Applicant: Mitsubishi Electric Corporation
    Inventors: Shuichi NAGATO, Miwako TANAKA, Akihiko IWATA
  • Patent number: 10840813
    Abstract: In a power conversion system in which self-excitation-type power conversion devices performing bidirectional power conversion are mutually interconnected by direct current, when the power conversion device serving for power transmission is stopped, in the first power conversion device, a DC capacitor voltage control unit calculates a current amount for compensating capacitor voltage in accordance with voltage variation in a DC capacitor. A high-voltage-side DC current control unit determines that an electricity amount supplied from a power supply system to the first power conversion device is a predetermined value or higher, and subtracts the current amount for compensating the capacitor voltage from a DC current command value. Thus, while the DC voltage is kept to be constant, the power flow direction is changed and power transmission to a second DC system is continued.
    Type: Grant
    Filed: May 12, 2017
    Date of Patent: November 17, 2020
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Miwako Tanaka, Toshiyuki Fujii
  • Publication number: 20200274456
    Abstract: In a power conversion system in which self-excitation-type power conversion devices performing bidirectional power conversion are mutually interconnected by direct current, when the power conversion device serving for power transmission is stopped, in the first power conversion device, a DC capacitor voltage control unit calculates a current amount for compensating capacitor voltage in accordance with voltage variation in a DC capacitor. A high-voltage-side DC current control unit determines that an electricity amount supplied from a power supply system to the first power conversion device is a predetermined value or higher, and subtracts the current amount for compensating the capacitor voltage from a DC current command value. Thus, while the DC voltage is kept to be constant, the power flow direction is changed and power transmission to a second DC system is continued.
    Type: Application
    Filed: May 12, 2017
    Publication date: August 27, 2020
    Applicant: Mitsubishi Electric Corporation
    Inventors: Miwako TANAKA, Toshiyuki FUJII
  • Publication number: 20200052485
    Abstract: A DC transmission system transmits AC power generated by a generator to an AC distribution grid and a DC distribution grid using DC power. The DC transmission system includes an AC/DC converter, a DC/DC converter, and a DC/AC converter. The AC/DC converter outputs DC power by converting AC power from the generator. The DC/DC converter boosts a first voltage of the DC power outputted from the AC/DC converter, into a second voltage. The DC/AC converter outputs, to the AC distribution grid, AC power by converting the DC power outputted from the DC/DC converter. When the second voltage changes, the DC/DC converter controls the first voltage in response to the change in the second voltage.
    Type: Application
    Filed: September 7, 2017
    Publication date: February 13, 2020
    Applicant: Mitsubishi Electric Corporation
    Inventors: Miwako TANAKA, Toshiyuki FUJII
  • Patent number: 9806630
    Abstract: A power conversion device performs power conversion between three-phase AC, and DC, and includes a positive arm and a negative arm for each phase, each of which includes one or more converter cells connected in series. A voltage command generating unit in a control device includes an AC current control unit, a circulating current control unit, and a command distributing unit, and generates a positive arm voltage command and a negative arm voltage command for each phase. In the circulating current control unit, a compensator calculates a first control command so that circulating current for each phase approaches a circulating current command value, a suppression unit generates a second control command so as to suppress a 2f component and a 4f component contained in the first control command, and then the first control command and the second control command are combined to generate a circulation control command.
    Type: Grant
    Filed: July 23, 2015
    Date of Patent: October 31, 2017
    Assignees: Mitsubishi Electric Corporation, TOSHIBA MITSUBISHI-ELECTRIC INDUSTRIAL SYSTEMS CORPORATION
    Inventors: Kaho Mukunoki, Toshiyuki Fujii, Miwako Tanaka, Osamu Mori, Shinzo Tamai, Sadao Funahashi, Yasuhiko Hosokawa, Kotaro Higashi
  • Publication number: 20170214334
    Abstract: A power conversion device performs power conversion between three-phase AC, and DC, and includes a positive arm and a negative arm for each phase, each of which includes one or more converter cells connected in series. A voltage command generating unit in a control device includes an AC current control unit, a circulating current control unit, and a command distributing unit, and generates a positive arm voltage command and a negative arm voltage command for each phase. In the circulating current control unit, a compensator calculates a first control command so that circulating current for each phase approaches a circulating current command value, a suppression unit generates a second control command so as to suppress a 2f component and a 4f component contained in the first control command, and then the first control command and the second control command are combined to generate a circulation control command.
    Type: Application
    Filed: July 23, 2015
    Publication date: July 27, 2017
    Applicants: Mitsubishi Electric Corporation, TOSHIBA MITSUBISHI-ELECTRIC INDUSTRIAL SYSTEMS CORPORATION
    Inventors: Kaho MUKUNOKI, Toshiyuki FUJII, Miwako TANAKA, Osamu MORI, Shinzo TAMAI, Sadao FUNAHASHI, Yasuhiko HOSOKAWA, Kotaro HIGASHI