Patents by Inventor Akeshi Takahashi

Akeshi Takahashi 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).

  • Publication number: 20220224270
    Abstract: A winding switching device switches parallel and series connections of windings of a rotating electric machine, and includes a plurality of electrodes that are connected to the windings and a power source, a movable portion in contact with the plurality of electrodes and includes a plurality of conductor portions, and an actuator that drives the movable portion. According to a contact state between the plurality of electrodes and the plurality of conductor portions, the windings are connected in parallel at a first position of the movable portion, and are connected in series at a second position of the movable portion. The electrodes include a first electrode connected to a first phase winding of the rotating electric machine in the plurality of windings, and a second electrode connected to a second phase winding. The first electrode and the second electrode are adjacent to each other, and form a neutral point.
    Type: Application
    Filed: March 23, 2020
    Publication date: July 14, 2022
    Applicant: Hitachi, Ltd.
    Inventors: Shinji SUGIMOTO, Akeshi TAKAHASHI, Kazuo NISHIHAMA
  • Patent number: 11233474
    Abstract: A rotating machine drive system includes: a rotating machine that includes a plurality of windings; a phase current detecting circuit that detects a phase current to be supplied to the rotating machine; an inverter device that includes an inverter circuit that converts DC power from a DC power supply into AC power, and a control device that controls power conversion being performed by an inverter main circuit on the basis of the phase current detected by the phase current detecting circuit, the inverter device operating the rotating machine at a variable speed; and a winding switching device that switches connections of the plurality of windings in accordance with a command from the control device.
    Type: Grant
    Filed: December 11, 2018
    Date of Patent: January 25, 2022
    Assignee: Hitachi, Ltd.
    Inventors: Akeshi Takahashi, Yoshitaka Iwaji, Shinji Sugimoto
  • Publication number: 20220006411
    Abstract: A rotary machine driving system includes: a rotary machine including a plurality of coils; an inverter device configured to operate the rotary machine at a variable speed, including a control device for controlling power conversion by an inverter circuit, and a coil switching device for switching a connection of the coils according to the control device. The control device commands the coil switching device to switch the connection of the coils when rotation of the rotary machine transitions between a low-speed rotation range and a high-speed rotation range due to acceleration and deceleration. A starting end and a terminal end of at least one set of coils per phase of the rotary machine are drawn out in a freely connectable state. The coil switching device includes at least one movable portion driven by one actuator.
    Type: Application
    Filed: June 21, 2019
    Publication date: January 6, 2022
    Applicant: HITACHI, LTD.
    Inventors: Akeshi TAKAHASHI, Shinji SUGIMOTO, Kazuo NISHIHAMA
  • Publication number: 20210384779
    Abstract: An object of the present invention is to provide a highly efficient and highly reliable rotary electric machine. A rotary electric machine includes: a stator around which a plurality of coils are wound; and a rotor which is supported to be freely rotatable with a predetermined gap with respect to the stator. The coil has at least one connection portion per turn in a slot of the stator. Conductors to be connected mutually have steps at the connection portion, and are fitted with other conductors so as to mutually fill the steps. The steps have contact surfaces that come into contact with each other in the slot to be electrically conducted. A thermally expandable sheet capable of pressurizing the coil in a radial direction of the stator is arranged in the slot.
    Type: Application
    Filed: January 8, 2020
    Publication date: December 9, 2021
    Inventors: Akeshi TAKAHASHI, Minori NAGATA, Masanori SAWAHATA
  • Publication number: 20210044238
    Abstract: A rotating machine drive system includes: a rotating machine that includes a plurality of windings; a phase current detecting circuit that detects a phase current to be supplied to the rotating machine; an inverter device that includes an inverter circuit that converts DC power from a DC power supply into AC power, and a control device that controls power conversion being performed by an inverter main circuit on the basis of the phase current detected by the phase current detecting circuit, the inverter device operating the rotating machine at a variable speed; and a winding switching device that switches connections of the plurality of windings in accordance with a command from the control device.
    Type: Application
    Filed: December 11, 2018
    Publication date: February 11, 2021
    Inventors: Akeshi TAKAHASHI, Yoshitaka IWAJI, Shinji SUGIMOTO
  • Patent number: 10658905
    Abstract: A rotating electrical machine includes a rotating electrical machine body including a stator, a rotor, a fan configured to circulate a coolant for cooling the stator and the rotor, and a casing containing the stator, the rotor and the fan; and a cooler connected to the rotating electrical machine body. The coolant flows from the machine body into the cooler. The cooler cools the coolant. The coolant flows out of the cooler into the machine body. The cooler has a flow resistance Ra satisfying a relation 0.15<(Ra/Rm)<(P0/P1), wherein Ra is a flow resistance of the coolant in the cooler, Rm is a flow resistance of the coolant in the rotating electrical machine body, P0 is a shutoff pressure of the fan, and P1 is a pressure at an operating point of the fan when the flow resistance Ra of the cooler is assumed to be zero.
    Type: Grant
    Filed: September 7, 2018
    Date of Patent: May 19, 2020
    Assignee: Hitachi Industrial Products, Ltd.
    Inventors: Ryuuichirou Iwano, Masanori Sawahata, Akeshi Takahashi
  • Patent number: 10270303
    Abstract: In a permanent magnet electric motor, a plurality of projections are formed at least partially along an axial direction in the magnet insertion openings, the projection positioning both edges of the permanent magnet in the circumferential direction so that vacant spaces are defined at each sides of the permanent magnet in the circumferential direction; a plurality of slits arranged along the circumferential direction are provided in regions, the region being positioned radially outward from the permanent magnet and being sandwiched at the edges of the permanent magnet in the circumferential direction by the projections; and the shortest distance between the slit and the magnet insertion opening is set to be greater than the shortest distance between the slit and an outer circumferential surface of the rotor core.
    Type: Grant
    Filed: March 31, 2014
    Date of Patent: April 23, 2019
    Assignee: Hitachi-Johnson Controls Air Conditioning, Inc.
    Inventors: Yusuke Asaumi, Akihiro Ishikawa, Akeshi Takahashi
  • Publication number: 20190109514
    Abstract: A rotating electrical machine includes a rotating electrical machine body including a stator, a rotor, a fan configured to circulate a coolant for cooling the stator and the rotor, and a casing containing the stator, the rotor and the fan; and a cooler connected to the rotating electrical machine body. The coolant flows from the machine body into the cooler. The cooler cools the coolant. The coolant flows out of the cooler into the machine body. The cooler has a flow resistance Ra satisfying a relation 0.15<(Ra/Rm)<(P0/P1), wherein Ra is a flow resistance of the coolant in the cooler, Rm is a flow resistance of the coolant in the rotating electrical machine body, P0 is a shutoff pressure of the fan, and P1 is a pressure at an operating point of the fan when the flow resistance Ra of the cooler is assumed to be zero.
    Type: Application
    Filed: September 7, 2018
    Publication date: April 11, 2019
    Inventors: Ryuuichirou IWANO, Masanori SAWAHATA, Akeshi TAKAHASHI
  • Publication number: 20160072347
    Abstract: In a permanent magnet electric motor, a plurality of projections are formed at least partially along an axial direction in the magnet insertion openings, the projection positioning both edges of the permanent magnet in the circumferential direction so that vacant spaces are defined at each sides of the permanent magnet in the circumferential direction; a plurality of slits arranged along the circumferential direction are provided in regions, the region being positioned radially outward from the permanent magnet and being sandwiched at the edges of the permanent magnet in the circumferential direction by the projections; and the shortest distance between the slit and the magnet insertion opening is set to be greater than the shortest distance between the slit and an outer circumferential surface of the rotor core.
    Type: Application
    Filed: March 31, 2014
    Publication date: March 10, 2016
    Inventors: Yusuke ASAUMI, Akihiro ISHIKAWA, Akeshi TAKAHASHI
  • Patent number: 8729762
    Abstract: To provide a permanent magnet synchronous machine capable of expanding a high-speed operation range without reducing torque, and a pressing machine or an extrusion machine using the permanent magnet synchronous machine. In order to achieve the object described above, the present invention provides a permanent magnet synchronous electric machine having at least one permanent magnet on a radial surface of a rotor core, the permanent magnet having a rotor constituting a field pole, wherein a plurality of slits constituted by nonmagnetic material is provided on a core part between adjacent permanent magnets with opposite magnetic polarities of the rotor. According to the present invention, expansion of a high-speed operation range can be achieved without reducing torque.
    Type: Grant
    Filed: February 23, 2011
    Date of Patent: May 20, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Akeshi Takahashi, Shinichi Wakui
  • Publication number: 20110241466
    Abstract: To provide a permanent magnet synchronous machine capable of expanding a high-speed operation range without reducing torque, and a pressing machine or an extrusion machine using the permanent magnet synchronous machine. In order to achieve the object described above, the present invention provides a permanent magnet synchronous electric machine having at least one permanent magnet on a radial surface of a rotor core, the permanent magnet having a rotor constituting a field pole, wherein a plurality of slits constituted by nonmagnetic material is provided on a core part between adjacent permanent magnets with opposite magnetic polarities of the rotor. According to the present invention, expansion of a high-speed operation range can be achieved without reducing torque.
    Type: Application
    Filed: February 23, 2011
    Publication date: October 6, 2011
    Inventors: Akeshi TAKAHASHI, Shinichi Wakui
  • Patent number: 7902713
    Abstract: A self-starting type permanent magnet synchronous motor comprises a stator and a rotor. The rotor comprises a rotor core having a plurality of slots provided in an outer periphery thereof and a cage winding comprising conductive bars embedded in the slots and conductive end rings that short-circuit the conductive bars on both end faces of the bars in an axial direction thereof. The rotor core comprises at least one magnet insertion hole arranged on an inner peripheral side from the slots, and at least one permanent magnet embedded in the at least one magnet insertion hole. When a pole center axis is denoted as a d-axis and an axis deviating from the pole center axis by an electrical angle 90° is denoted as a q-axis, a flux content generated by the cage winding during start-up becomes maximal in the vicinity of and on one of the d-axis and the q-axis.
    Type: Grant
    Filed: December 17, 2008
    Date of Patent: March 8, 2011
    Assignee: Hitachi Appliances, Inc.
    Inventors: Satoshi Kikuchi, Hiroyuki Mikami, Akeshi Takahashi, Tomio Yoshikawa, Keiji Tanaka, Masashi Miyake, Baiying Huang, Masaru Ohtahara, Kenji Tojo, Hideyuki Kumakura
  • Patent number: 7772736
    Abstract: The inventive self-initiated permanent magnet synchronous motor has a rotor that has two-pole permanent magnets, as well as magnetic substances in a peripheral direction between the magnetic poles of the permanent magnets. The present invention provides a high-efficiency, high-torque permanent magnet synchronous motor with an improved power factor, its rotor, and a compressor using the permanent magnet synchronous motor, without a reduction in the maximum torque and an increase in costs.
    Type: Grant
    Filed: June 5, 2007
    Date of Patent: August 10, 2010
    Assignee: Hitachi Appliances, Inc.
    Inventors: Akeshi Takahashi, Haruo Koharagi, Satoshi Kikuchi, Tomio Yoshikawa, Baiying Huang
  • Patent number: 7592734
    Abstract: A three-phase permanent magnet brushless motor comprises a stator having three-phase windings, and a rotor having a permanent magnet with a plurality of poles for serving as a field magnet. The stator comprises a stator core which includes a powder core that is compacted at a high density in at least teeth thereof. A combination of the number of magnetic poles of the rotor with the number of slots of the stator satisfies a condition that a least common multiple of the number of slots and the number of magnetic poles is 60 or more in a region in which the number of magnetic poles is 16 or less, and the number of slots is 12 or less. The powder core is made by compacting magnetic powders to have a green density of 7.5 g/cm3 or higher.
    Type: Grant
    Filed: August 17, 2006
    Date of Patent: September 22, 2009
    Assignees: Hitachi Industrial Equipment System Co., Ltd., Japan Servo Co., Ltd., Hitachi Powered Metals Co., Ltd.
    Inventors: Yuji Enomoto, Akeshi Takahashi, Motoya Ito, Ryoso Masaki, Katsuyuki Yamazaki, Masahide Yamazaki, Masashi Kitamura, Chio Ishihara, Kazuo Asaka, Shoji Ohiwa, Yasuaki Motegi
  • Publication number: 20090200885
    Abstract: The present invention provides a permanent magnet that a fluorine compound is formed on the surfaces of Fe-based magnetic particles, and a recoil permeability is determined in a range of 1.05 to 1.30 by controlling an iron concentration in the fluorine compound to a range of 1 to 50% to reduce a loss due to magnetization rotation, thereby remedying reduction of a residual magnetic flux density and degradation of steady-state characteristics.
    Type: Application
    Filed: December 23, 2008
    Publication date: August 13, 2009
    Inventors: Satoshi Kikuchi, Yuuichi Satsuu, Matahiro Komuro, Hiroyuki Mikami, Akeshi Takahashi
  • Publication number: 20090160285
    Abstract: A self-starting type permanent magnet synchronous motor comprises a stator and a rotor. The rotor comprises a rotor core having a plurality of slots provided in an outer periphery thereof and a cage winding comprising conductive bars embedded in the slots and conductive end rings that short-circuit the conductive bars on both end faces of the bars in an axial direction thereof. The rotor core comprises at least one magnet insertion hole arranged on an inner peripheral side from the slots, and at least one permanent magnet embedded in the at least one magnet insertion hole. When a pole center axis is denoted as a d-axis and an axis deviating from the pole center axis by an electrical angle 90° is denoted as a q-axis, a flux content generated by the cage winding during start-up becomes maximal in the vicinity of and on one of the d-axis and the q-axis.
    Type: Application
    Filed: December 17, 2008
    Publication date: June 25, 2009
    Inventors: Satoshi Kikuchi, Hiroyuki Mikami, Akeshi Takahashi, Tomio Yoshikawa, Keiji Tanaka, Masashi Miyake, Baiying Huang, Masaru Ohtahara, Kenji Tojo, Hideyuki Kumakura
  • Patent number: 7531934
    Abstract: In a method of manufacturing a self-start synchronous motor for preventing deterioration of permanent magnets used in a rotor, and also for enhancing the efficiency of the self-start synchronous motor, the self-start synchronous motor comprising a stator having a stator core and windings wound around the stator core, and a rotor having an outer diameter slightly smaller than an inner diameter of the stator and arranged inside of the stator. The rotor is provided with a rotor core, a plurality of conductor bars embedded in the outer peripheral portion of the rotor core over an entire periphery thereof, end rings provided on opposite end sides of the conductor bars and constituting a squirrel cage conductor in cooperation with the conductor bars, and a plurality of permanent magnets embedded in the rotor core and arranged at a position inner than that of an inner peripheral surface of the conductor bars.
    Type: Grant
    Filed: May 25, 2006
    Date of Patent: May 12, 2009
    Assignee: Hitachi Appliances, Inc.
    Inventors: Baiying Hang, Tomio Yoshikawa, Yasuro Ohishi, Akeshi Takahashi, Haruo Koharagi
  • Patent number: 7501734
    Abstract: The invention provides a motor comprising a stator and a rotor. The stator core includes a laminated stator core made of laminated stator core plates in which straight cut surfaces are formed on a circular outer peripheral surface of the laminated stator core plates. The straight cut surfaces of the laminated stator core plates are circumferentially displaced every predetermined laminated stator core plates so that the straight cut surfaces are uniformly distributed in an axial and a circumferential direction of the laminated stator core. Therefore, a flow passage for lubricating oil is ensured, while local magnetic saturation of the stator core is dissolved and a cogging torque and an induced voltage waveform distortion rate are improved.
    Type: Grant
    Filed: February 17, 2006
    Date of Patent: March 10, 2009
    Assignee: Hitachi Appliances, Inc.
    Inventors: Akeshi Takahashi, Tomio Yoshikawa, Baiying Huang, Shigekazu Nozawa, Susumu Nakayaka, Haruo Koharagi, Satoshi Kikuchi
  • Patent number: 7453181
    Abstract: A permanent magnet synchronous motor includes a rotor having cage windings and permanent magnets placed on an inner peripheral side of these cage winding bars, where the permanent magnets are placed and polarized so that a ratio ?/? between a circumferential pitch angle ? of magnetic flux distribution of the permanent magnets and a magnet pole pitch angle ? is between 0.67 and 0.91.
    Type: Grant
    Filed: December 28, 2006
    Date of Patent: November 18, 2008
    Assignee: Hitachi Appliances, Inc.
    Inventors: Satoshi Kikuchi, Haruo Koharagi, Akeshi Takahashi, Tomio Yoshikawa, Baiying Huang
  • Publication number: 20080238235
    Abstract: A self-starting permanent magnet synchronous motor which demonstrates satisfactory acceleration performance even at a reduced supply voltage or with an increased load torque, and a compressor using the same. The motor comprises a stator having a stator winding and a rotor having a cage winding and a permanent magnet on the rotor core. The torque component generated by the cage winding is maximal at 1 in the slip range of 0 to 1.
    Type: Application
    Filed: January 25, 2008
    Publication date: October 2, 2008
    Inventors: Akeshi TAKAHASHI, Satoshi Kikuchi, Hiroyuki Mikami, Kazuo Nishihama, Tomio Yoshikawa, Baiying Huang