Patents by Inventor Ryoichi Takahata

Ryoichi Takahata 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: 9325264
    Abstract: An electric motor drive device 1000 includes: an inverter 3 that drives a motor 4, a voltage division circuit 2 that serves as a neutral point potential detection unit that detects a neutral point potential of a stator winding of the motor 4; and a controller 1 that estimates a rotor position of the motor 4 based on the detected neutral point potential, and that controls the inverter 3 based on an estimation result. A ground potential of the controller 1 is set to a negative side potential or a positive side potential of a DC voltage that is supplied to the inverter 3. The voltage division circuit 2 detects the neutral point potential with reference to the negative side potential or the positive side potential.
    Type: Grant
    Filed: April 12, 2012
    Date of Patent: April 26, 2016
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Iwaji, Ryoichi Takahata, Takahiro Suzuki
  • Publication number: 20150155805
    Abstract: An electric motor drive device 1000 includes: an inverter 3 that drives a motor 4, a voltage division circuit 2 that serves as a neutral point potential detection unit that detects a neutral point potential of a stator winding of the motor 4; and a controller 1 that estimates a rotor position of the motor 4 based on the detected neutral point potential, and that controls the inverter 3 based on an estimation result. A ground potential of the controller 1 is set to a negative side potential or a positive side potential of a DC voltage that is supplied to the inverter 3. The voltage division circuit 2 detects the neutral point potential with reference to the negative side potential or the positive side potential.
    Type: Application
    Filed: April 12, 2012
    Publication date: June 4, 2015
    Applicant: Hitachi, Ltd.
    Inventors: Yoshitaka Iwaji, Ryoichi Takahata, Takahiro Suzuki
  • Publication number: 20150069941
    Abstract: A three-phase synchronous motor drive device includes: a three-phase inverter 3 that drives a motor 4 that is as a three-phase synchronous motor, and that includes switching elements for three phases; a controller 2 that functions as a control unit that selects four switched states from a plurality of switched states that represent on/off states of the switching elements for the three phases, and that sequentially controls the three-phase inverter in the four switched states; a neutral point potential amplifier 13 that functions as a neutral point potential detection unit that detects a neutral point potential Vn0 of stator windings (Lu, Lv, Lw) of the motor 4 in each of the four switched states. It is configured that a rotor position of the three-phase synchronous motor is estimated over a full range of an electrical angle cycle based on at least three of four neutral point potentials detected in the four switched states.
    Type: Application
    Filed: April 12, 2012
    Publication date: March 12, 2015
    Applicant: Hitachi, Ltd.
    Inventors: Yoshitaka Iwaji, Ryoichi Takahata, Takahiro Suzuki
  • Patent number: 8884575
    Abstract: A drive system of a synchronous electrical motor includes a synchronous electrical motor; a power converter that is connected to the motor with a plurality of switching elements; a controller that outputs a voltage instruction to the power converter; a voltage detection unit for open phases upon application of respective positive and negative pulse voltages between respective two phases out of three-phase windings of the motor; an induced voltage difference for calculating an induced voltage difference that is a difference between an induced voltage detected by the voltage detection unit at each of the open phases upon application of the positive voltage pulse between the corresponding two phases and an induced voltage detected by the voltage detection unit at the open phase upon application of the negative voltage pulse between the two phases.
    Type: Grant
    Filed: April 9, 2013
    Date of Patent: November 11, 2014
    Assignee: Hitachi Automotive Systems, Ltd.
    Inventors: Ryoichi Takahata, Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari
  • Patent number: 8878480
    Abstract: In sequentially selecting and driving two phases of the three-phase stator windings of a synchronous motor, detect a speed electromotive voltage of a de-energized phase, relate the speed electromotive voltage to rotor position information beforehand, then count rotor position information backward based on the detected the speed electromotive voltage to estimate rotor position; and then detect rotation speed from the change rate of the rotor position information so as to achieve highly accurate position and speed control.
    Type: Grant
    Filed: July 26, 2012
    Date of Patent: November 4, 2014
    Assignee: Hitachi Automotive Systems, Ltd.
    Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata, Masaki Hano
  • Patent number: 8766575
    Abstract: A synchronous electric motor drive system capable of driving at speeds near zero is provided. An energization mode determination unit switches six energization modes successively based on a terminal potential detected of the de-energized phase of a three-phase synchronous electric motor or on a stator winding wire connection point potential (neutral point potential) detected of the three-phase synchronous transmission unit. A voltage command correction unit corrects by a correction amount ?V an applied voltage command destined for the synchronous electric motor to supply the synchronous electric motor with a repeated waveform of a positive pulse, negative pulse, and zero voltage as a line voltage waveform of the energized phases in each of the six energization modes, the positive pulse voltage being polarized to cause the synchronous electric motor to generate a forward rotation torque, the negative pulse voltage causing the synchronous electric motor to generate a reverse rotation torque.
    Type: Grant
    Filed: July 26, 2011
    Date of Patent: July 1, 2014
    Assignees: Hitachi Automotive Systems, Ltd., Hitachi Car Engineering Co., Ltd.
    Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata
  • Publication number: 20140077738
    Abstract: A position sensor-less driving method is provided that can drive rotation speed/torque control of a permanent magnet motor using an inverter with an ideal sinusoidal current with the minimum number of switching, and can drive at a speed as low as an extremely low speed region close to zero speed. A neutral point potential of a permanent magnet motor is detected in synchronization with PWM waveform of the inverter. A rotor position of the permanent magnet motor is estimated from change of the neutral point potential. When the neutral point potential is detected, timing of each phase of the PWM waveform is shifted to generate three or four types of switch states of which output voltage of the inverter is not zero vector, and neutral point potentials in at least two types of switch states among them are sampled, whereby rotor position of the three-phase synchronous motor is estimated.
    Type: Application
    Filed: May 13, 2011
    Publication date: March 20, 2014
    Applicant: Hitachi, Ltd.
    Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Ryoichi Takahata, Kazuaki Tobari
  • Publication number: 20130272899
    Abstract: A drive system of a synchronous electrical motor includes a synchronous electrical motor; a power converter that is connected to the motor with a plurality of switching elements; a controller that outputs a voltage instruction to the power converter; a voltage detection unit for open phases upon application of respective positive and negative pulse voltages between respective two phases out of three-phase windings of the motor; an induced voltage difference for calculating an induced voltage difference that is a difference between an induced voltage detected by the voltage detection unit at each of the open phases upon application of the positive voltage pulse between the corresponding two phases and an induced voltage detected by the voltage detection unit at the open phase upon application of the negative voltage pulse between the two phases.
    Type: Application
    Filed: April 9, 2013
    Publication date: October 17, 2013
    Applicant: HITACHI AUTOMOTIVE SYSTEMS, LTD.
    Inventors: Ryoichi TAKAHATA, Yoshitaka IWAJI, Shigehisa AOYAGI, Kazuaki TOBARI
  • Publication number: 20130243625
    Abstract: A synchronous electric motor drive system capable of driving at speeds near zero is provided. An energization mode determination unit switches six energization modes successively based on a terminal potential detected of the de-energized phase of a three-phase synchronous electric motor or on a stator winding wire connection point potential (neutral point potential) detected of the three-phase synchronous transmission unit. A voltage command correction unit corrects by a correction amount ?V an applied voltage command destined for the synchronous electric motor to supply the synchronous electric motor with a repeated waveform of a positive pulse, negative pulse, and zero voltage as a line voltage waveform of the energized phases in each of the six energization modes, the positive pulse voltage being polarized to cause the synchronous electric motor to generate a forward rotation torque, the negative pulse voltage causing the synchronous electric motor to generate a reverse rotation torque.
    Type: Application
    Filed: July 26, 2011
    Publication date: September 19, 2013
    Applicants: Hitachi Car Engineering Co., Ltd., Hitachi Automotive Systems, Ltd.
    Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata
  • Publication number: 20130057193
    Abstract: In sequentially selecting and driving two phases of the three-phase stator windings of a synchronous motor, detect a speed electromotive voltage of a de-energized phase, relate the speed electromotive voltage to rotor position information beforehand, then count rotor position information backward based on the detected the speed electromotive voltage to estimate rotor position; and then detect rotation speed from the change rate of the rotor position information so as to achieve highly accurate position and speed control.
    Type: Application
    Filed: July 26, 2012
    Publication date: March 7, 2013
    Applicant: Hitachi Automotive Systems, Ltd.
    Inventors: Yoshitaka Iwaji, Shigehisa Aoyagi, Kazuaki Tobari, Ryoichi Takahata, Masaki Hano
  • Patent number: 7915776
    Abstract: A permanent magnet type electric rotary machine includes a stator including a stator core having teeth and slots, and a rotor provided with permanent magnets as magnet poles in a rotor core. A pole core portion which between each of the permanent magnets and an outer surface of the rotor core is provided with a plurality of pole slits. A region of the pole core portion is defined by concave portions provided on q-axes to be interpolars on both sides of the pole core portion, and thereby configured that a gap between the outer surface on the q-axis of the rotor core and an inner surface of the stator core is larger than a gap between the outer surface on the d-axis of the pole core portion and the inner surface of the stator, so that magnetic fluxes from the permanent magnet pass through the pole core portion concentrately.
    Type: Grant
    Filed: June 15, 2010
    Date of Patent: March 29, 2011
    Assignee: Hitachi Industrial Equipment Systems Co., Ltd.
    Inventors: Ryoichi Takahata, Satoshi Kikuchi, Shinichi Wakui, Keiji Noma, Masaharu Senoo
  • Publication number: 20100244609
    Abstract: A permanent magnet type electric rotary machine includes a stator including a stator core having teeth and slots, and a rotor provided with permanent magnets as magnet poles in a rotor core. A pole core portion which between each of the permanent magnets and an outer surface of the rotor core is provided with a plurality of pole slits. A region of the pole core portion is defined by concave portions provided on q-axes to be interpolars on both sides of the pole core portion, and thereby configured that a gap between the outer surface on the q-axis of the rotor core and an inner surface of the stator core is larger than a gap between the outer surface on the d-axis of the pole core portion and the inner surface of the stator, so that magnetic fluxes from the permanent magnet pass through the pole core portion concentrately.
    Type: Application
    Filed: June 15, 2010
    Publication date: September 30, 2010
    Inventors: Ryoichi Takahata, Satoshi Kikuchi, Shinichi Wakui, Keiji Noma, Masaharu Senoo
  • Patent number: 7768172
    Abstract: A permanent magnet type electric rotary machine includes a stator including a stator core having teeth and slots, and a rotor provided with permanent magnets as magnet poles in a rotor core. A pole core portion which between each of the permanent magnets and an outer surface of the rotor core is provided with a plurality of pole slits. A region of the pole core portion is defined by concave portions provided on q-axes to be interpolars on both sides of the pole core portion, and thereby configured that a gap between the outer surface on the q-axis of the rotor core and an inner surface of the stator core is larger than a gap between the outer surface on the d-axis of the pole core portion and the inner surface of the stator, so that magnetic fluxes from the permanent magnet pass through the pole core portion concentrately.
    Type: Grant
    Filed: July 19, 2007
    Date of Patent: August 3, 2010
    Assignee: Hitachi Industrial Equipment Systems Co., Ltd.
    Inventors: Ryoichi Takahata, Satoshi Kikuchi, Shinichi Wakui, Keiji Noma, Masaharu Senoo
  • Publication number: 20080018190
    Abstract: A permanent magnet type electric rotary machine includes a stator including a stator core having teeth and slots, and a rotor provided with permanent magnets as magnet poles in a rotor core. A pole core portion which between each of the permanent magnets and an outer surface of the rotor core is provided with a plurality of pole slits. A region of the pole core portion is defined by concave portions provided on q-axes to be interpolars on both sides of the pole core portion, and thereby configured that a gap between the outer surface on the q-axis of the rotor core and an inner surface of the stator core is larger than a gap between the outer surface on the d-axis of the pole core portion and the inner surface of the stator, so that magnetic fluxes from the permanent magnet pass through the pole core portion concentrately.
    Type: Application
    Filed: July 19, 2007
    Publication date: January 24, 2008
    Inventors: Ryoichi TAKAHATA, Satoshi Kikuchi, Shinichi Wakui, Keiji Noma, Masaharu Senoo
  • Patent number: 7057327
    Abstract: A vehicular alternator is provided which can effectively utilize the magnetic flux of a permanent magnet disposed between claw-type magnetic poles and can improve an output of the alternator. The vehicular alternator comprises a rotor and a stator constituted by coiling stator windings over a stator core, the rotor comprising a pair of claw-type magnetic poles arranged in an opposed relation, a permanent magnet disposed between adjacent two of a plurality of claws provided on the pair of claw-type magnetic poles, and field windings coiled radially inward of the plurality of claws. Each of the plurality of claws of the rotor is formed to have a shape coming into contact with the whole of a magnetic pole surface of the permanent magnet.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: June 6, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Kanazawa, Kenji Miyata, Kaoru Kawabata, Kohji Maki, Kazuo Tahara, Susumu Sasaki, Ryoichi Takahata
  • Patent number: 6838798
    Abstract: In a permanent magnet type rotating electric machine comprising a stator of which concentratedly wound armature windings are disposed in a plurality of slots formed in a stator core so as to surround teeth and a rotor accommodating permanent magnets in a plurality of permanent magnet insertion holes formed in a rotor core, a part of outer circumferential faces of slots is formed to extend substantially in parallel with a part of inner circumferential faces of the teeth, thereby, a permanent magnet type rotating electric machine with limited noises can be realized.
    Type: Grant
    Filed: January 8, 2003
    Date of Patent: January 4, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Takahata, Shinichi Wakui, Haruo Koharagi, Satoshi Kikuchi, Miyoshi Takahashi, Masaharu Senoh, Keiji Noma, Hiroshi Hirayama, Takashi Seshimo, Shigeya Kawaminami
  • Patent number: 6759777
    Abstract: A permanent magnetic type electric rotating machine includes: a stator having armature winding arranged in several slots formed in a stator core; and a rotor having permanent magnets held in several permanent magnetic insertion holes formed in a rotor core, in which a peripheral surface of the rotor core is configured to be a combination of arcs around two points different from a center of the rotor core for each magnetic pole in such a manner that when an axis extending in a central direction of a magnetic pole of the rotor is a d axis, and an axis extending in a direction between magnetic poles that is offset from the central direction of the magnetic pole by 90 electrical degrees is a q axis, a radial distance from a center of the rotor core to a periphery of the rotor is reduced gradually from the d axis to the q axis.
    Type: Grant
    Filed: July 30, 2002
    Date of Patent: July 6, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Takahata, Shinichi Wakui, Haruo Koharagi, Satoshi Kikuchi, Miyoshi Takahashi
  • Patent number: 6759776
    Abstract: A permanent magnetic type electric rotating machine includes: a stator having armature winding arranged in several slots formed in a stator core; and a rotor having permanent magnets held in several permanent magnetic insertion holes formed in a rotor core, in which a peripheral surface of the rotor core is configured to be a combination of arcs around two points different from a center of the rotor core for each magnetic pole in such a manner that when an axis extending in a central direction of a magnetic pole of the rotor is a d axis, and an axis extending in a direction between magnetic poles that is offset from the central direction of the magnetic pole by 90 electrical degrees is a q axis, a radial distance from a center of the rotor core to a periphery of the rotor is reduced gradually from the d axis to the q axis.
    Type: Grant
    Filed: March 20, 2002
    Date of Patent: July 6, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Takahata, Shinichi Wakui, Haruo Koharagi, Satoshi Kikuchi, Miyoshi Takahashi
  • Publication number: 20030107291
    Abstract: In a permanent magnet type rotating electric machine comprising a stator of which concentratedly wound armature windings are disposed in a plurality of slots formed in a stator core so as to surround teeth and a rotor accommodating permanent magnets in a plurality of permanent magnet insertion holes formed in a rotor core, a part of outer circumferential faces of slots is formed to extend substantially in parallel with a part of inner circumferential faces of the teeth, thereby, a permanent magnet type rotating electric machine with limited noises can be realized.
    Type: Application
    Filed: January 8, 2003
    Publication date: June 12, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Ryoichi Takahata, Shinichi Wakui, Haruo Koharagi, Satoshi Kikuchi, Miyoshi Takahashi, Masaharu Senoh, Keiji Noma, Hiroshi Hirayama, Takashi Seshimo, Shigeya Kawaminami
  • Patent number: 6552461
    Abstract: In a permanent magnet type rotating electric machine comprising a stator of which concentratedly wound armature windings are disposed in a plurality of slots formed in a stator core so as to surround teeth and a rotor accommodating permanent magnets in a plurality of permanent magnet insertion holes formed in a rotor core, a part of outer circumferential faces of slots is formed to extend substantially in parallel with a part of inner circumferential faces of the teeth, thereby, a permanent magnet type rotating electric machine with limited noises can be realized.
    Type: Grant
    Filed: March 6, 2002
    Date of Patent: April 22, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Takahata, Shinichi Wakui, Haruo Koharagi, Satoshi Kikuchi, Miyoshi Takahashi, Masaharu Senoh, Keiji Noma, Hiroshi Hirayama, Takashi Seshimo, Shigeya Kawaminami