Patents by Inventor Takeru MURAO
Takeru MURAO 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).
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Patent number: 9722507Abstract: An electric power conversion apparatus according to an embodiment includes, wherein when a constituent element constituted of a leg in which two switching elements provided with self-arc-extinguishing capability are connected in series, and a capacitor connected in parallel with the leg is made a converter unit, and a constituent element formed by connecting one or more converter units in series is made a phase arm, a phase arm on the positive side, a single-phase four-winding transformer, and a phase arm on the negative side are included in each of three phases, one end of the phase arm on the positive side is connected to the positive side of a secondary winding of the four-winding transformer, and the other end thereof is connected to a DC positive side terminal.Type: GrantFiled: May 1, 2015Date of Patent: August 1, 2017Assignee: KABUSHIKI KAISHA TOSHIBAInventors: Yosuke Nakazawa, Takeru Murao, Shunsuke Tamada
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Patent number: 9379548Abstract: A reactive power compensator according to an embodiment comprises: multilevel inverter circuits respectively constituting each of the three phases; a filter circuit for reducing harmonics connected between the output terminals of each of the multilevel inverter circuits and a power system interconnection terminal; and a control section for causing prescribed three-phase AC voltage to be output by controlling each of said multilevel inverter circuits. Each of the multilevel inverter circuits is constituted by connecting in series one or more single-phase full-bridge single-pulse inverters and is arranged to convert DC voltage to respective positive and negative single-pulse voltages once per cycle of the fundamental wave of the voltage instruction value.Type: GrantFiled: November 14, 2013Date of Patent: June 28, 2016Assignee: Kabushiki Kaisha ToshibaInventors: Yushi Koyama, Yosuke Nakazawa, Hiroshi Mochikawa, Atsuhiko Kuzumaki, Takeru Murao
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Patent number: 9369065Abstract: An inexpensive and space-saving power conversion device is provided which can eliminate a high-cost and large reactor like a buffer reactor. A device includes multiple switching elements 21u, 21x performing conversion between DC and AC upon switching, a unitary unit C including the switching elements 21u, 21x, and a capacitor 30, and unit arms 10P, 10N each including at least one unitary unit C. The primary side of a transformer 40 is connected between the pair of unit arms 10P, 10N so as to suppress a short-circuit current by a leakage inductance component.Type: GrantFiled: May 23, 2014Date of Patent: June 14, 2016Assignee: KABUSHIKI KAISHA TOSHIBAInventors: Yosuke Nakazawa, Takeru Murao, Masahiro Tsumenaga
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Publication number: 20150236611Abstract: An electric power conversion apparatus according to an embodiment includes, wherein when a constituent element constituted of a leg in which two switching elements provided with self-arc-extinguishing capability are connected in series, and a capacitor connected in parallel with the leg is made a converter unit, and a constituent element formed by connecting one or more converter units in series is made a phase arm, a phase arm on the positive side, a single-phase four-winding transformer, and a phase arm on the negative side are included in each of three phases, one end of the phase arm on the positive side is connected to the positive side of a secondary winding of the four-winding transformer, and the other end thereof is connected to a DC positive side terminal.Type: ApplicationFiled: May 1, 2015Publication date: August 20, 2015Applicant: Kabushiki Kaisha ToshibaInventors: Yosuke NAKAZAWA, Takeru MURAO, Shunsuke TAMADA
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Patent number: 8836311Abstract: Provided is a power converter having a switching circuit wherein a surge voltage of a plurality of switching elements connected in series is suppressed and loss is not concentrated to a specific switching element. The switching circuit is provided with: a non-latching type switching element having two main terminals and one control terminal; a voltage detecting means which detects a voltage applied between the main terminals of the switching element; a control current supply for supplying the control terminal with a control signal corresponding to the voltage detected by the voltage detector; and a delay device for delaying the control signal.Type: GrantFiled: April 9, 2010Date of Patent: September 16, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Hiromichi Tai, Takeru Murao
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Publication number: 20140254226Abstract: An inexpensive and space-saving power conversion device is provided which can eliminate a high-cost and large reactor like a buffer reactor. A device includes multiple switching elements 21u, 21x performing conversion between DC and AC upon switching, a unitary unit C including the switching elements 21u, 21x, and a capacitor 30, and unit arms 10P, 10N each including at least one unitary unit C. The primary side of a transformer 40 is connected between the pair of unit arms 10P, 10N so as to suppress a short-circuit current by a leakage inductance component.Type: ApplicationFiled: May 23, 2014Publication date: September 11, 2014Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Yosuke Nakazawa, Takeru Murao, Masahiro Tsumenaga
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Publication number: 20140133198Abstract: A reactive power compensator according to an embodiment comprises: multilevel inverter circuits respectively constituting each of the three phases; a filter circuit for reducing harmonics connected between the output terminals of each of the multilevel inverter circuits and a power system interconnection terminal; and a control section for causing prescribed three-phase AC voltage to be output by controlling each of said multilevel inverter circuits. Each of the multilevel inverter circuits is constituted by connecting in series one or more single-phase full-bridge single-pulse inverters and is arranged to convert DC voltage to respective positive and negative single-pulse voltages once per cycle of the fundamental wave of the voltage instruction value.Type: ApplicationFiled: November 14, 2013Publication date: May 15, 2014Inventors: Yushi Koyama, Yosuke Nakazawa, Hiroshi Mochikawa, Atsuhiko Kuzumaki, Takeru Murao
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Patent number: 8649198Abstract: Disclosed is a power conversion device which achieves reductions in switching loss due to a reverse recovery current and heat generation loss. Specifically disclosed is a power conversion device provided with a cascode element configured by electrically connecting a normally-on switching element and a normally-off switching element in series and connecting a gate terminal of the normally-on switching element and a source terminal of the normally-off switching element via a cascode connection diode, and a high-speed diode electrically connected in parallel with the cascode element and having a cathode region connected to a positive electrode terminal and an anode region connected to a negative electrode terminal.Type: GrantFiled: December 20, 2011Date of Patent: February 11, 2014Assignees: Kabushiki Kaisha Toshiba, Central Research Institute of Electric Power IndustryInventors: Atsuhiko Kuzumaki, Hiroshi Mochikawa, Takeru Murao, Masahiro Takasaki, Tadao Ishikawa, Toshiaki Kikuma
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Publication number: 20120087167Abstract: Disclosed is a power conversion device which achieves reductions in switching loss due to a reverse recovery current and heat generation loss. Specifically disclosed is a power conversion device provided with a cascode element configured by electrically connecting a normally-on switching element and a normally-off switching element in series and connecting a gate terminal of the normally-on switching element and a source terminal of the normally-off switching element via a cascode connection diode, and a high-speed diode electrically connected in parallel with the cascode element and having a cathode region connected to a positive electrode terminal and an anode region connected to a negative electrode terminal.Type: ApplicationFiled: December 20, 2011Publication date: April 12, 2012Applicants: Central Research Institute of Electric Power Ind., KABUSHIKI KAISHA TOSHIBAInventors: Atsuhiko KUZUMAKI, Hiroshi MOCHIKAWA, Takeru MURAO, Masahiro TAKASAKI, Tadao ISHIKAWA, Toshiaki KIKUMA
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Publication number: 20100219877Abstract: Provided is a power converter having a switching circuit wherein a surge voltage of a plurality of switching elements connected in series is suppressed and loss is not concentrated to a specific switching element. The switching circuit is provided with: a non-latching type switching element having two main terminals and one control terminal; a voltage detecting means which detects a voltage applied between the main terminals of the switching element; a control current supply for supplying the control terminal with a control signal corresponding to the voltage detected by the voltage detector; and a delay device for delaying the control signal.Type: ApplicationFiled: April 9, 2010Publication date: September 2, 2010Applicant: Kabushiki Kaisha ToshibaInventors: Hiromichi TAI, Takeru MURAO